ORACLE, SQL, PL/SQL Made very very Easy Happy Learning....

ORACLE
Hi all,
This is Oracle , SQL, PL-SQL Document which is made easy for
the beginners and as well as Intermediates.
Happy Learning….
Topics Covered:
 INTRODUCTION
 CONDITIONAL SELECTIONS AND OPERATORS
 MULTIBLE INSERTS
 FUNCTIONS
 CONSTRAINTS
 CASE AND DEFAULT
 ABSTRACT DATA TYPES
 OBJECT VIEWS AND METHODS
 VARRAYS AND NESTED TABLES
 FLASHBACK QUERY
 EXTERNAL TABLES
 REF DEREF VALUE
 OBJECT VIEWS WITH REFERENCES
 PARTITIONS
 ROLLUP GROUPING CUBE
 SET OPERATORS
 VIEWS
 SYNONYM AND SEQUENCE
 JOINS
 SUBQUERIES AND EXISTS
 WALKUP TREES AND INLINE VIEW
 LOCKS
 INDEXES
 SET COMMANDS
 SPECIAL FILES
 IMP QUERIES
 SQL
 PL-SQL
 ERROR HANDLING
 DATABASE TRIGGERS & etc……..

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INTRODUCTION
SQL is divided into the following
 Data Definition Language (DDL)
 Data Manipulation Language (DML)
 Data Retrieval Language (DRL)
 Transaction Control Language (TCL)
 Data Control Language (DCL)
DDL -- create, alter, drop, truncate, rename
DML -- insert, update, delete
DRL -- select
TCL -- commit, rollback, savepoint
DCL -- grant, revoke
CREATE TABLE SYNTAX
Create table <table_name> (col1 datatype1, col2 datatype2 …coln datatypen);
Ex:
SQL> create table student (no number (2), name varchar (10), marks number (3));
INSERT
This will be used to insert the records into table.
We have two methods to insert.
 By value method
 By address method
a) USING VALUE METHOD
Syntax:
insert into <table_name) values (value1, value2, value3 …. Valuen);
Ex:
SQL> insert into student values (1, ’sudha’, 100);

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SQL> insert into student values (2, ’saketh’, 200);
To insert a new record again you have to type entire insert command, if there are lot of
records this will be difficult.
This will be avoided by using address method.
b) USING ADDRESS METHOD
Syntax:
insert into <table_name> values (&col1, &col2, &col3 …. &coln);
This will prompt you for the values but for every insert you have to use forward slash.
Ex:
SQL> insert into student values (&no, '&name', &marks);
Enter value for no: 1
Enter value for name: Jagan
Enter value for marks: 300
old 1: insert into student values(&no, '&name', &marks)
new 1: insert into student values(1, 'Jagan', 300)
SQL> /
Enter value for name: Naren
Enter value for marks: 400
old 1: insert into student values(&no, '&name', &marks)
new 1: insert into student values(2, 'Naren', 400)
c) INSERTING DATA INTO SPECIFIED COLUMNS USING VALUE METHOD
Syntax:
insert into <table_name)(col1, col2, col3 … Coln) values (value1, value2, value3 ….
Valuen);
Ex:
SQL> insert into student (no, name) values (3, ’Ramesh’);
SQL> insert into student (no, name) values (4, ’Madhu’);

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d) INSERTING DATA INTO SPECIFIED COLUMNS USING ADDRESS METHOD
Syntax:
insert into <table_name)(col1, col2, col3 … coln) values (&col1, &col2, &col3 ….
&coln);
This will prompt you for the values but for every insert you have to use forward slash.
Ex:
SQL> insert into student (no, name) values (&no, '&name');
Enter value for name: Visu
old 1: insert into student (no, name) values(&no, '&name')
new 1: insert into student (no, name) values(5, 'Visu')
SQL> /
Enter value for name: Rattu
old 1: insert into student (no, name) values(&no, '&name')
new 1: insert into student (no, name) values(6, 'Rattu')
SELECTING DATA
Syntax:
Select * from <table_name>; -- here * indicates all columns
or
Select col1, col2, … coln from <table_name>;
Ex:
SQL> select * from student;
NO NAME MARKS
--- ------ --------
1 Sudha 100
2 Saketh 200
1 Jagan 300
2 Naren 400
3 Ramesh
4 Madhu

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5 Visu
6 Rattu
SQL> select no, name, marks from student;
NO NAME MARKS
--- ------ --------
1 Sudha 100
2 Saketh 200
1 Jagan 300
2 Naren 400
3 Ramesh
4 Madhu
5 Visu
6 Rattu
SQL> select no, name from student;
NO NAME
--- -------
1 Sudha
2 Saketh
1 Jagan
2 Naren
3 Ramesh
4 Madhu
5 Visu
6 Rattu

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CONDITIONAL SELECTIONS AND OPERATORS
We have two clauses used in this
 Where
 Order by
USING WHERE
Syntax:
select * from <table_name> where <condition>;
the following are the different types of operators used in where clause.
 Arithmetic operators
 Comparison operators
 Logical operators
 Arithmetic operators -- highest precedence
+, -, *, /
 Comparison operators
 =, !=, >, <, >=, <=, <>
 between, not between
 in, not in
 null, not null
 like
 Logical operators
 And
 Or -- lowest precedence
 not
a) USING =, >, <, >=, <=, !=, <>
Ex:
SQL> select * from student where no = 2;
NO NAME MARKS
--- ------- ---------
2 Saketh 200

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2 Naren 400
SQL> select * from student where no < 2;
NO NAME MARKS
--- ------- ----------
1 Sudha 100
1 Jagan 300
SQL> select * from student where no > 2;
NO NAME MARKS
--- ------- ----------
3 Ramesh
4 Madhu
5 Visu
6 Rattu
SQL> select * from student where no <= 2;
NO NAME MARKS
--- ------- ----------
1 Sudha 100
2 Saketh 200
1 Jagan 300
2 Naren 400
SQL> select * from student where no >= 2;
NO NAME MARKS
--- ------- ---------
2 Saketh 200
2 Naren 400
3 Ramesh
4 Madhu
5 Visu
6 Rattu

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SQL> select * from student where no != 2;
NO NAME MARKS
--- ------- ----------
1 Sudha 100
1 Jagan 300
3 Ramesh
4 Madhu
5 Visu
6 Rattu
SQL> select * from student where no <> 2;
NO NAME MARKS
--- ------- ----------
1 Sudha 100
1 Jagan 300
3 Ramesh
4 Madhu
5 Visu
6 Rattu
b) USING AND
This will gives the output when all the conditions become true.
Syntax:
select * from <table_name> where <condition1> and <condition2> and ..
<conditionn>;
Ex:
SQL> select * from student where no = 2 and marks >= 200;
NO NAME MARKS
--- ------- --------
2 Saketh 200

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2 Naren 400
c) USING OR
This will gives the output when either of the conditions become true.
Syntax:
select * from <table_name> where <condition1> and <condition2> or ..
<conditionn>;
Ex:
SQL> select * from student where no = 2 or marks >= 200;
NO NAME MARKS
--- ------- ---------
2 Saketh 200
1 Jagan 300
2 Naren 400
d) USING BETWEEN
This will gives the output based on the column and its lower bound, upperbound.
Syntax:
select * from <table_name> where <col> between <lower bound> and <upper
bound>;
Ex:
SQL> select * from student where marks between 200 and 400;
NO NAME MARKS
--- ------- ---------
2 Saketh 200
1 Jagan 300
2 Naren 400

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e) USING NOT BETWEEN
This will gives the output based on the column which values are not in its lower bound,
upperbound.
Syntax:
select * from <table_name> where <col> not between <lower bound> and <upper
bound>;
Ex:
SQL> select * from student where marks not between 200 and 400;
NO NAME MARKS
--- ------- ---------
1 Sudha 100
f) USING IN
This will gives the output based on the column and its list of values specified.
Syntax:
select * from <table_name> where <col> in ( value1, value2, value3 … valuen);
Ex:
SQL> select * from student where no in (1, 2, 3);
NO NAME MARKS
--- ------- ---------
1 Sudha 100
2 Saketh 200
1 Jagan 300
2 Naren 400
3 Ramesh
g) USING NOT IN
This will gives the output based on the column which values are not in the list of values
specified.

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Syntax:
select * from <table_name> where <col> not in ( value1, value2, value3 … valuen);
Ex:
SQL> select * from student where no not in (1, 2, 3);
NO NAME MARKS
--- ------- ---------
4 Madhu
5 Visu
6 Rattu
h) USING NULL
This will gives the output based on the null values in the specified column.
Syntax:
select * from <table_name> where <col> is null;
Ex:
SQL> select * from student where marks is null;
NO NAME MARKS
--- ------- ---------
3 Ramesh
4 Madhu
5 Visu
6 Rattu
i) USING NOT NULL
This will gives the output based on the not null values in the specified column.
Syntax:
select * from <table_name> where <col> is not null;

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Ex:
SQL> select * from student where marks is not null;
NO NAME MARKS
--- ------- ---------
1 Sudha 100
2 Saketh 200
1 Jagan 300
2 Naren 400
j) USING LIKE
This will be used to search through the rows of database column based on the pattern you
specify.
Syntax:
select * from <table_name> where <col> like <pattern>;
Ex:
i) This will give the rows whose marks are 100.
SQL> select * from student where marks like 100;
NO NAME MARKS
--- ------- ---------
1 Sudha 100
ii) This will give the rows whose name start with ‘S’.
SQL> select * from student where name like 'S%';
NO NAME MARKS
--- ------- ---------
1 Sudha 100
2 Saketh 200
iii) This will give the rows whose name ends with ‘h’.
SQL> select * from student where name like '%h';

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NO NAME MARKS
--- ------- ---------
2 Saketh 200
3 Ramesh
iV) This will give the rows whose name’s second letter start with ‘a’.
SQL> select * from student where name like '_a%';
NO NAME MARKS
--- ------- --------
2 Saketh 200
1 Jagan 300
2 Naren 400
3 Ramesh
4 Madhu
6 Rattu
V) This will give the rows whose name’s third letter start with ‘d’.
SQL> select * from student where name like '__d%';
NO NAME MARKS
--- ------- ---------
1 Sudha 100
4 Madhu
Vi) This will give the rows whose name’s second letter start with ‘t’ from ending.
SQL> select * from student where name like '%_t%';
NO NAME MARKS
--- ------- ---------
2 Saketh 200
6 Rattu
Vii) This will give the rows whose name’s third letter start with ‘e’ from ending.

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SQL> select * from student where name like '%e__%';
NO NAME MARKS
--- ------- ---------
2 Saketh 200
3 Ramesh
Viii) This will give the rows whose name cotains 2 a’s.
SQL> select * from student where name like '%a% a %';
NO NAME MARKS
--- ------- ----------
1 Jagan 300
* You have to specify the patterns in like using underscore ( _ ).
USING ORDER BY
This will be used to ordering the columns data (ascending or descending).
Syntax:
Select * from <table_name> order by <col> desc;
By default oracle will use ascending order.
If you want output in descending order you have to use desc keyword after the column.
Ex:
SQL> select * from student order by no;
NO NAME MARKS
--- ------- ---------
1 Sudha 100
1 Jagan 300
2 Saketh 200
2 Naren 400
3 Ramesh
4 Madhu

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5 Visu
6 Rattu
SQL> select * from student order by no desc;
NO NAME MARKS
--- ------- ---------
6 Rattu
5 Visu
4 Madhu
3 Ramesh
2 Saketh 200
2 Naren 400
1 Sudha 100
1 Jagan 300
USING DML
USING UPDATE
This can be used to modify the table data.
Syntax:
Update <table_name> set <col1> = value1, <col2> = value2 where <condition>;
Ex:
SQL> update student set marks = 500;
If you are not specifying any condition this will update entire table.
SQL> update student set marks = 500 where no = 2;
SQL> update student set marks = 500, name = 'Venu' where no = 1;
USING DELETE
This can be used to delete the table data temporarily.

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Syntax:
Delete <table_name> where <condition>;
Ex:
SQL> delete student;
If you are not specifying any condition this will delete entire table.
SQL> delete student where no = 2;
USING DDL
USING ALTER
This can be used to add or remove columns and to modify the precision of the datatype.
a) ADDING COLUMN
Syntax:
alter table <table_name> add <col datatype>;
Ex:
SQL> alter table student add sdob date;
b) REMOVING COLUMN
Syntax:
alter table <table_name> drop <col datatype>;
Ex:
SQL> alter table student drop column sdob;
c) INCREASING OR DECREASING PRECISION OF A COLUMN
Syntax:
alter table <table_name> modify <col datatype>;
Ex:
SQL> alter table student modify marks number(5);

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* To decrease precision the column should be empty.
d) MAKING COLUMN UNUSED
Syntax:
alter table <table_name> set unused column <col>;
Ex:
SQL> alter table student set unused column marks;
Even though the column is unused still it will occupy memory.
d) DROPPING UNUSED COLUMNS
Syntax:
alter table <table_name> drop unused columns;
Ex:
SQL> alter table student drop unused columns;
* You can not drop individual unused columns of a table.
e) RENAMING COLUMN
Syntax:
alter table <table_name> rename column <old_col_name> to <new_col_name>;
Ex:
SQL> alter table student rename column marks to smarks;
USING TRUNCATE
This can be used to delete the entire table data permanently.
Syntax:
truncate table <table_name>;
Ex:
SQL> truncate table student;
USING DROP

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This will be used to drop the database object;
Syntax:
Drop table <table_name>;
Ex:
SQL> drop table student;
USING RENAME
This will be used to rename the database object;
Syntax:
rename <old_table_name> to <new_table_name>;
Ex:
SQL> rename student to stud;
USING TCL
USING COMMIT
This will be used to save the work.
Commit is of two types.
 Implicit
 Explicit
a) IMPLICIT
This will be issued by oracle internally in two situations.
 When any DDL operation is performed.
 When you are exiting from SQL * PLUS.
b) EXPLICIT
This will be issued by the user.

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Syntax:
Commit or commit work;
* When ever you committed then the transaction was completed.
USING ROLLBACK
This will undo the operation.
This will be applied in two methods.
 Upto previous commit
 Upto previous rollback
Syntax:
Roll or roll work;
Or
Rollback or rollback work;
* While process is going on, if suddenly power goes then oracle will rollback the transaction.
USING SAVEPOINT
You can use savepoints to rollback portions of your current set of transactions.
Syntax:
Savepoint <savepoint_name>;
Ex:
SQL> savepoint s1;
SQL> insert into student values(1, ‘a’, 100);
SQL> savepoint s2;
SQL> insert into student values(2, ‘b’, 200);
SQL> savepoint s3;
SQL> insert into student values(3, ‘c’, 300);
SQL> savepoint s4;
SQL> insert into student values(4, ‘d’, 400);
Before rollback
NO NAME MARKS

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--- ------- ----------
1 a 100
2 b 200
3 c 300
4 d 400
SQL> rollback to savepoint s3;
Or
SQL> rollback to s3;
This will rollback last two records.
NO NAME MARKS
--- ------- ----------
1 a 100
2 b 200
USING DCL
DCL commands are used to granting and revoking the permissions.
USING GRANT
This is used to grant the privileges to other users.
Syntax:
Grant <privileges> on <object_name> to <user_name> [with grant option];
Ex:
SQL> grant select on student to sudha; -- you can give individual privilege
SQL> grant select, insert on student to sudha; -- you can give set of privileges
SQL> grant all on student to sudha; -- you can give all privileges
The sudha user has to use dot method to access the object.
SQL> select * from saketh.student;
The sudha user can not grant permission on student table to other users. To get this type
of

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option use the following.
SQL> grant all on student to sudha with grant option;
Now sudha user also grant permissions on student table.
USING REVOKE
This is used to revoke the privileges from the users to which you granted the privileges.
Syntax:
Revoke <privileges> on <object_name> from <user_name>;
Ex:
SQL> revoke select on student form sudha; -- you can revoke individual privilege
SQL> revoke select, insert on student from sudha; -- you can revoke set of privileges
SQL> revoke all on student from sudha; -- you can revoke all privileges
USING ALIASES
CREATE WITH SELECT
We can create a table using existing table [along with data].
Syntax:
Create table <new_table_name> [col1, col2, col3 ... coln] as select * from
<old_table_name>;
Ex:
SQL> create table student1 as select * from student;
Creating table with your own column names.
SQL> create table student2(sno, sname, smarks) as select * from student;
Creating table with specified columns.
SQL> create table student3 as select no,name from student;
Creating table with out table data.

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SQL> create table student2(sno, sname, smarks) as select * from student where 1 = 2;
In the above where clause give any condition which does not satisfy.
INSERT WITH SELECT
Using this we can insert existing table data to a another table in a single trip. But the table
structure should be same.
Syntax:
Insert into <table1> select * from <table2>;
Ex:
SQL> insert into student1 select * from student;
Inserting data into specified columns
SQL> insert into student1(no, name) select no, name from student;
COLUMN ALIASES
Syntax:
Select <orginal_col> <alias_name> from <table_name>;
Ex:
SQL> select no sno from student;
or
SQL> select no “sno” from student;
TABLE ALIASES
If you are using table aliases you can use dot method to the columns.
Syntax:
Select <alias_name>.<col1>, <alias_name>.<col2> … <alias_name>.<coln> from
<table_name> <alias_name>;
Ex:
SQL> select s.no, s.name from student s;

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USING MERGE
MERGE
You can use merge command to perform insert and update in a single command.
Ex:
SQL> Merge into student1 s1
Using (select *From student2) s2
On(s1.no=s2.no)
When matched then
Update set marks = s2.marks
When not matched then
Insert (s1.no,s1.name,s1.marks)
Values(s2.no,s2.name,s2.marks);
In the above the two tables are with the same structure but we can merge different
structured
tables also but the datatype of the columns should match.
Assume that student1 has columns like no,name,marks and student2 has columns like no,
name, hno, city.
SQL> Merge into student1 s1
Using (select *From student2) s2
On(s1.no=s2.no)
When matched then
Update set marks = s2.hno
When not matched then
Insert (s1.no,s1.name,s1.marks)
Values(s2.no,s2.name,s2.hno);

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MULTIBLE INSERTS
We have table called DEPT with the following columns and data
DEPTNO DNAME LOC
-------- -------- ----
10 accounting new york
20 research dallas
30 sales Chicago
40 operations boston
a) CREATE STUDENT TABLE
SQL> Create table student(no number(2),name varchar(2),marks number(3));
b) MULTI INSERT WITH ALL FIELDS
SQL> Insert all
Into student values(1,’a’,100)
Into student values(2,’b’,200)
Into student values(3,’c’,300)
Select *from dept where deptno=10;
-- This inserts 3 rows
c) MULTI INSERT WITH SPECIFIED FIELDS
SQL> insert all
Into student (no,name) values(4,’d’)
Into student(name,marks) values(’e’,400)
d) MULTI INSERT WITH DUPLICATE ROWS
SQL> insert all

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Into student values(1,’a’,100)
Into student values(2,’b’,200)
Select *from dept where deptno > 10;
-- This inserts 9 rows because in the select statement retrieves 3 records (3 inserts for
each
row retrieved)
e) MULTI INSERT WITH CONDITIONS BASED
SQL> Insert all
When deptno > 10 then
Into student1 values(1,’a’,100)
When dname = ‘SALES’ then
Into student2 values(2,’b’,200)
When loc = ‘NEW YORK’ then
Into student3 values(3,’c’,300)
Select *from dept where deptno>10;
-- This inserts 4 rows because the first condition satisfied 3 times, second condition
satisfied once and the last none.
f) MULTI INSERT WITH CONDITIONS BASED AND ELSE
SQL> Insert all
When deptno > 100 then
When dname = ‘S’ then
Else
Into student values(4,’d’,400)
Select *from dept where deptno>10;
-- This inserts 3 records because the else satisfied 3 times

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g) MULTI INSERT WITH CONDITIONS BASED AND FIRST
SQL> Insert first
When deptno = 20 then
When dname = ‘RESEARCH’ then
-- This inserts 1 record because the first clause avoid to check the remaining conditions
once the condition is satisfied.
h) MULTI INSERT WITH CONDITIONS BASED, FIRST AND ELSE
SQL> Insert first
When deptno = 30 then
When dname = ‘R’ then
Else
Into student values(4,’d’,400)
-- This inserts 1 record because the else clause satisfied once
i) MULTI INSERT WITH MULTIBLE TABLES
SQL> Insert all

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** You can use multi tables with specified fields, with duplicate rows, with conditions,
with
first and else clauses.

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FUNCTIONS
Functions can be categorized as follows.
 Single row functions
 Group functions
SINGLE ROW FUNCTIONS
Single row functions can be categorized into five. These will be applied for each row and
produces individual output for each row.
 Numeric functions
 String functions
 Date functions
 Miscellaneous functions
 Conversion functions
NUMERIC FUNCTIONS
 Abs
 Sign
 Sqrt
 Mod
 Nvl
 Power
 Exp
 Ln
 Log
 Ceil
 Floor
 Round
 Trunk
 Bitand
 Greatest
 Least
 Coalesce
a) ABS

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Absolute value is the measure of the magnitude of value.
Absolute value is always a positive number.
Syntax: abs (value)
Ex:
SQL> select abs(5), abs(-5), abs(0), abs(null) from dual;
ABS(5) ABS(-5) ABS(0) ABS(NULL)
---------- ---------- ---------- -------------
5 -5 0
b) SIGN
Sign gives the sign of a value.
Syntax: sign (value)
Ex:
SQL> select sign(5), sign(-5), sign(0), sign(null) from dual;
SIGN(5) SIGN(-5) SIGN(0) SIGN(NULL)
---------- ---------- ---------- --------------
1 -1 0
c) SQRT
This will give the square root of the given value.
Syntax: sqrt (value) -- here value must be positive.
Ex:
SQL> select sqrt(4), sqrt(0), sqrt(null), sqrt(1) from dual;
SQRT(4) SQRT(0) SQRT(NULL) SQRT(1)
---------- ---------- --------------- ----------
2 0 1

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d) MOD
This will give the remainder.
Syntax: mod (value, divisor)
Ex:
SQL> select mod(7,4), mod(1,5), mod(null,null), mod(0,0), mod(-7,4) from dual;
MOD(7,4) MOD(1,5) MOD(NULL,NULL) MOD(0,0) MOD(-7,4)
------------ ---------- --------------------- ----------- -------------
3 1 0 -3
e) NVL
This will substitutes the specified value in the place of null values.
Syntax: nvl (null_col, replacement_value)
Ex:
SQL> select * from student; -- here for 3rd
row marks value is null
NO NAME MARKS
--- ------- ---------
1 a 100
2 b 200
3 c
SQL> select no, name, nvl(marks,300) from student;
NO NAME NVL(MARKS,300)
--- ------- ---------------------
1 a 100
2 b 200
3 c 300
SQL> select nvl(1,2), nvl(2,3), nvl(4,3), nvl(5,4) from dual;

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NVL(1,2) NVL(2,3) NVL(4,3) NVL(5,4)
---------- ---------- ---------- ----------
1 2 4 5
SQL> select nvl(0,0), nvl(1,1), nvl(null,null), nvl(4,4) from dual;
NVL(0,0) NVL(1,1) NVL(null,null) NVL(4,4)
---------- ---------- ----------------- ----------
0 1 4
f) POWER
Power is the ability to raise a value to a given exponent.
Syntax: power (value, exponent)
Ex:
SQL> select power(2,5), power(0,0), power(1,1), power(null,null), power(2,-5) from
dual;
POWER(2,5) POWER(0,0) POWER(1,1) POWER(NULL,NULL) POWER(2,-5)
-------------- -------------- ----- --------- ----------------------- ---------------
32 1 1 .03125
g) EXP
This will raise e value to the give power.
Syntax: exp (value)
Ex:
SQL> select exp(1), exp(2), exp(0), exp(null), exp(-2) from dual;
EXP(1) EXP(2) EXP(0) EXP(NULL) EXP(-2)
-------- --------- -------- ------------- ----------
2.71828183 7.3890561 1 .135335283

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h) LN
This is based on natural or base e logarithm.
Syntax: ln (value) -- here value must be greater than zero which is positive only.
Ex:
SQL> select ln(1), ln(2), ln(null) from dual;
LN(1) LN(2) LN(NULL)
------- ------- ------------
0 .693147181
Ln and Exp are reciprocal to each other.
EXP (3) = 20.0855369
LN (20.0855369) = 3
i) LOG
This is based on 10 based logarithm.
Syntax: log (10, value)-- here value must be greater than zero which is positive only.
Ex:
SQL> select log(10,100), log(10,2), log(10,1), log(10,null) from dual;
LOG(10,100) LOG(10,2) LOG(10,1) LOG(10,NULL)
--------------- ----------- ------------ -----------------
2 .301029996 0
LN (value) = LOG (EXP(1), value)
SQL> select ln(3), log(exp(1),3) from dual;
LN(3) LOG(EXP(1),3)
------- -----------------
1.09861229 1.09861229

ORACLE
j) CEIL
This will produce a whole number that is greater than or equal to the specified value.
Syntax: ceil (value)
Ex:
SQL> select ceil(5), ceil(5.1), ceil(-5), ceil( -5.1), ceil(0), ceil(null) from dual;
CEIL(5) CEIL(5.1) CEIL(-5) CEIL(-5.1) CEIL(0) CEIL(NULL)
--------- ----------- ---------- ------------ -------- --------------
5 6 -5 -5 0
k) FLOOR
This will produce a whole number that is less than or equal to the specified value.
Syntax: floor (value)
Ex:
SQL> select floor(5), floor(5.1), floor(-5), floor( -5.1), floor(0), floor(null) from dual;
FLOOR(5) FLOOR(5.1) FLOOR(-5) FLOOR(-5.1) FLOOR(0) FLOOR(NULL)
----------- ------------- ------------ -------------- ----------- ----------------
5 5 -5 -6 0
l) ROUND
This will rounds numbers to a given number of digits of precision.
Syntax: round (value, precision)
Ex:
SQL> select round(123.2345), round(123.2345,2), round(123.2354,2) from dual;
ROUND(123.2345) ROUND(123.2345,0) ROUND(123.2345,2)
ROUND(123.2354,2)

ORACLE
--------------------- ------------------------ ----------------------- ----------------------
-
123 123 123.23 123.24
SQL> select round(123.2345,-1), round(123.2345,-2), round(123.2345,-3),
round(123.2345,-4) from dual;
ROUND(123.2345,-1) ROUND(123.2345,-2) ROUND(123.2345,-3) ROUND(123.2345,-
4)
------------------------ ------------------------- ------------------------ -----------------------
-
120 100 0 0
SQL> select round(123,0), round(123,1), round(123,2) from dual;
ROUND(123,0) ROUND(123,1) ROUND(123,2)
----------------- ----------------- ----------------
123 123 123
SQL> select round(-123,0), round(-123,1), round(-123,2) from dual;
ROUND(-123,0) ROUND(-123,1) ROUND(-123,2)
------------------ ----------------- -------------------
-123 -123 -123
SQL> select round(123,-1), round(123,-2), round(123,-3), round(-123,-1), round(-
123,-
2), round(-123,-3) from dual;
ROUND(123,-1) ROUND(123,-2) ROUND(123,-3) ROUND(-123,-1) ROUND(-123,-2)
ROUND(-123,-3)
------------- ------------- ------------- -------------- -------------- --------------
120 100 0 -120 -100 0
SQL> select round(null,null), round(0,0), round(1,1), round(-1,-1), round(-2,-2) from
dual;
ROUND(NULL,NULL) ROUND(0,0) ROUND(1,1) ROUND(-1,-1) ROUND(-2,-2)
----------------------- -------------- -------------- ---------------- ----------------

ORACLE
0 1 0 0
m) TRUNC
This will truncates or chops off digits of precision from a number.
Syntax: trunc (value, precision)
Ex:
SQL> select trunc(123.2345), trunc(123.2345,2), trunc(123.2354,2) from dual;
TRUNC(123.2345) TRUNC(123.2345,2) TRUNC(123.2354,2)
--------------------- ----------------------- -----------------------
123 123.23 123.23
SQL> select trunc(123.2345,-1), trunc(123.2345,-2), trunc(123.2345,-3),
trunc(123.2345,-4) from dual;
TRUNC(123.2345,-1) TRUNC(123.2345,-2) TRUNC(123.2345,-3) TRUNC(123.2345,-4)
------------------------ ------------------------ ----------------------- ------------------------
120 100 0 0
SQL> select trunc(123,0), trunc(123,1), trunc(123,2) from dual;
TRUNC(123,0) TRUNC(123,1) TRUNC(123,2)
---------------- ---------------- -----------------
123 123 123
SQL> select trunc(-123,0), trunc(-123,1), trunc(-123,2) from dual;
TRUNC(-123,0) TRUNC(-123,1) TRUNC(-123,2)
----------------- ----------------- -----------------
-123 -123 -123
SQL> select trunc(123,-1), trunc(123,-2), trunc(123,-3), trunc(-123,-1), trunc(-123,2),
trunc(-123,-3) from dual;

ORACLE
TRUNC(123,-1) TRUNC(123,-2) TRUNC(123,-3) TRUNC(-123,-1) TRUNC(-123,2)
TRUNC(-
123,-3)
------------- ------------- ------------- -------------- ------------- --------------
120 100 0 -120 -123 0
SQL> select trunc(null,null), trunc(0,0), trunc(1,1), trunc(-1,-1), trunc(-2,-2) from
dual;
TRUNC(NULL,NULL) TRUNC(0,0) TRUNC(1,1) TRUNC(-1,-1) TRUNC(-2,-2)
----------------------- ------------- ------------- --------------- ----------------
0 1 0 0
n) BITAND
This will perform bitwise and operation.
Syntax: bitand (value1, value2)
Ex:
SQL> select bitand(2,3), bitand(0,0), bitand(1,1), bitand(null,null), bitand(-2,-3) from
dual;
BITAND(2,3) BITAND(0,0) BITAND(1,1) BITAND(NULL,NULL) BITAND(-2,-3)
-------------- --------------- -------------- ------------------------ -----------------
2 0 1 -4
o) GREATEST
This will give the greatest number.
Syntax: greatest (value1, value2, value3 … valuen)
Ex:
SQL> select greatest(1, 2, 3), greatest(-1, -2, -3) from dual;
GREATEST(1,2,3) GREATEST(-1,-2,-3)
-------------------- -----------------------
3 -1

ORACLE
 If all the values are zeros then it will display zero.
 If all the parameters are nulls then it will display nothing.
 If any of the parameters is null it will display nothing.
p) LEAST
This will give the least number.
Syntax: least (value1, value2, value3 … valuen)
Ex:
SQL> select least(1, 2, 3), least(-1, -2, -3) from dual;
LEAST(1,2,3) LEAST(-1,-2,-3)
-------------------- -----------------------
1 -3
 If all the values are zeros then it will display zero.
q) COALESCE
This will return first non-null value.
Syntax: coalesce (value1, value2, value3 … valuen)
Ex:
SQL> select coalesce(1,2,3), coalesce(null,2,null,5) from dual;
COALESCE(1,2,3) COALESCE(NULL,2,NULL,5)
------------------- -------------------------------
1 2
STRING FUNCTIONS
 Initcap
 Upper
 Lower
 Length

ORACLE
 Rpad
 Lpad
 Ltrim
 Rtrim
 Trim
 Translate
 Replace
 Soundex
 Concat ( ‘ || ‘ Concatenation operator)
 Ascii
 Chr
 Substr
 Instr
 Decode
 Greatest
 Least
 Coalesce
a) INITCAP
This will capitalize the initial letter of the string.
Syntax: initcap (string)
Ex:
SQL> select initcap('computer') from dual;
INITCAP
-----------
Computer
b) UPPER
This will convert the string into uppercase.
Syntax: upper (string)
Ex:
SQL> select upper('computer') from dual;

ORACLE
UPPER
-----------
COMPUTER
c) LOWER
This will convert the string into lowercase.
Syntax: lower (string)
Ex:
SQL> select lower('COMPUTER') from dual;
LOWER
-----------
computer
d) LENGTH
This will give length of the string.
Syntax: length (string)
Ex:
SQL> select length('computer') from dual;
LENGTH
-----------
8
e) RPAD
This will allows you to pad the right side of a column with any set of characters.
Syntax: rpad (string, length [, padding_char])
Ex:

ORACLE
SQL> select rpad('computer',15,'*'), rpad('computer',15,'*#') from dual;
RPAD('COMPUTER' RPAD('COMPUTER'
---------------------- ----------------------
computer******* computer*#*#*#*
-- Default padding character was blank space.
f) LPAD
This will allows you to pad the left side of a column with any set of characters.
Syntax: lpad (string, length [, padding_char])
Ex:
SQL> select lpad('computer',15,'*'), lpad('computer',15,'*#') from dual;
LPAD('COMPUTER' LPAD('COMPUTER'
--------------------- ---------------------
*******computer *#*#*#*computer
-- Default padding character was blank space.
g) LTRIM
This will trim off unwanted characters from the left end of string.
Syntax: ltrim (string [,unwanted_chars])
Ex:
SQL> select ltrim('computer','co'), ltrim('computer','com') from dual;
LTRIM( LTRIM
-------- ---------
mputer puter
SQL> select ltrim('computer','puter'), ltrim('computer','omputer') from dual;
LTRIM('C LTRIM('C

ORACLE
---------- ----------
computer computer
-- If you haven’t specify any unwanted characters it will display entire string.
h) RTRIM
This will trim off unwanted characters from the right end of string.
Syntax: rtrim (string [, unwanted_chars])
Ex:
SQL> select rtrim('computer','er'), rtrim('computer','ter') from dual;
RTRIM( RTRIM
-------- ---------
comput compu
SQL> select rtrim('computer','comput’), rtrim('computer','compute') from dual;
RTRIM('C RTRIM('C
---------- ----------
computer computer
-- If you haven’t specify any unwanted characters it will display entire string.
i) TRIM
This will trim off unwanted characters from the both sides of string.
Syntax: trim (unwanted_chars from string)
Ex:
SQL> select trim( 'i' from 'indiani') from dual;
TRIM(
-----
ndian
SQL> select trim( leading'i' from 'indiani') from dual; -- this will work as LTRIM

ORACLE
TRIM(L
------
ndiani
SQL> select trim( trailing'i' from 'indiani') from dual; -- this will work as RTRIM
TRIM(T
------
Indian
j) TRANSLATE
This will replace the set of characters, character by character.
Syntax: translate (string, old_chars, new_chars)
Ex:
SQL> select translate('india','in','xy') from dual;
TRANS
--------
xydxa
k) REPLACE
This will replace the set of characters, string by string.
Syntax: replace (string, old_chars [, new_chars])
Ex:
SQL> select replace('india','in','xy'), replace(‘india’,’in’) from dual;
REPLACE REPLACE
----------- -----------
Xydia dia

ORACLE
l) SOUNDEX
This will be used to find words that sound like other words, exclusively used in where
clause.
Syntax: soundex (string)
Ex:
SQL> select * from emp where soundex(ename) = soundex('SMIT');
EMPNO ENAME JOB MGR HIREDATE SAL DEPTNO
-------- -------- ----- ----- ------------ --------- ----------
7369 SMITH CLERK 7902 17-DEC-80 500 20
m) CONCAT
This will be used to combine two strings only.
Syntax: concat (string1, string2)
Ex:
SQL> select concat('computer',' operator') from dual;
CONCAT('COMPUTER'
-------------------------
computer operator
If you want to combine more than two strings you have to use concatenation operator
(||).
SQL> select 'how' || ' are' || ' you' from dual;
'HOW'||'ARE
---------------
how are you
n) ASCII
This will return the decimal representation in the database character set of the first

ORACLE
character of the string.
Syntax: ascii (string)
Ex:
SQL> select ascii('a'), ascii('apple') from dual;
ASCII('A') ASCII('APPLE')
------------ ------------------
97 97
o) CHR
This will return the character having the binary equivalent to the string in either the
database character set or the national character set.
Syntax: chr (number)
Ex:
SQL> select chr(97) from dual;
CHR
-----
a
p) SUBSTR
This will be used to extract substrings.
Syntax: substr (string, start_chr_count [, no_of_chars])
Ex:
SQL> select substr('computer',2), substr('computer',2,5), substr('computer',3,7) from
dual;
SUBSTR( SUBST SUBSTR
---------- ------- --------
omputer omput mputer
 If no_of_chars parameter is negative then it will display nothing.

ORACLE
 If both parameters except string are null or zeros then it will display nothing.
 If no_of_chars parameter is greater than the length of the string then it ignores
and calculates based on the orginal string length.
 If start_chr_count is negative then it will extract the substring from right end.
1 2 3 4 5 6 7 8
C O M P U T E R
-8 -7 -6 -5 -4 -3 -2 -1
q) INSTR
This will allows you for searching through a string for set of characters.
Syntax: instr (string, search_str [, start_chr_count [, occurrence] ])
Ex:
SQL> select instr('information','o',4,1), instr('information','o',4,2) from dual;
INSTR('INFORMATION','O',4,1) INSTR('INFORMATION','O',4,2)
------------------------------------ -------------------------------------
4 10
 If you are not specifying start_chr_count and occurrence then it will start search
from
the beginning and finds first occurrence only.
 If both parameters start_chr_count and occurrence are null, it will display nothing.
r) DECODE
Decode will act as value by value substitution.
For every value of field, it will checks for a match in a series of if/then tests.
Syntax: decode (value, if1, then1, if2, then2, ……. else);
Ex:
SQL> select sal, decode(sal,500,'Low',5000,'High','Medium') from emp;
SAL DECODE

ORACLE
----- ---------
500 Low
2500 Medium
2000 Medium
3500 Medium
3000 Medium
5000 High
4000 Medium
5000 High
1800 Medium
1200 Medium
2000 Medium
2700 Medium
2200 Medium
3200 Medium
SQL> select decode(1,1,3), decode(1,2,3,4,4,6) from dual;
DECODE(1,1,3) DECODE(1,2,3,4,4,6)
----------------- ------------------------
3 6
 If the number of parameters are odd and different then decode will display
nothing.
 If the number of parameters are even and different then decode will display last
value.
 If all the parameters are null then decode will display nothing.
 If all the parameters are zeros then decode will display zero.
s) GREATEST
This will give the greatest string.
Syntax: greatest (strng1, string2, string3 … stringn)
Ex:
SQL> select greatest('a', 'b', 'c'), greatest('satish','srinu','saketh') from dual;
GREAT GREAT

ORACLE
------- -------
c srinu
t) LEAST
This will give the least string.
Syntax: greatest (strng1, string2, string3 … stringn)
Ex:
SQL> select least('a', 'b', 'c'), least('satish','srinu','saketh') from dual;
LEAST LEAST
------- -------
a saketh
u) COALESCE
This will gives the first non-null string.
Syntax: coalesce (strng1, string2, string3 … stringn)
Ex:
SQL> select coalesce('a','b','c'), coalesce(null,'a',null,'b') from dual;
COALESCE COALESCE
----------- -----------
a a
DATE FUNCTIONS
 Sysdate
 Current_date

ORACLE
 Current_timestamp
 Systimestamp
 Localtimestamp
 Dbtimezone
 Sessiontimezone
 To_char
 To_date
 Add_months
 Months_between
 Next_day
 Last_day
 Extract
 Greatest
 Least
 Round
 Trunc
 New_time
 Coalesce
Oracle default date format is DD-MON-YY.
We can change the default format to our desired format by using the following command.
SQL> alter session set nls_date_format = ‘DD-MONTH-YYYY’;
But this will expire once the session was closed.
a) SYSDATE
This will give the current date and time.
Ex:
SQL> select sysdate from dual;
SYSDATE
-----------
24-DEC-06
b) CURRENT_DATE
This will returns the current date in the session’s timezone.

ORACLE
Ex:
SQL> select current_date from dual;
CURRENT_DATE
------------------
24-DEC-06
c) CURRENT_TIMESTAMP
This will returns the current timestamp with the active time zone information.
Ex:
SQL> select current_timestamp from dual;
CURRENT_TIMESTAMP
---------------------------------------------------------------------------
24-DEC-06 03.42.41.383369 AM +05:30
d) SYSTIMESTAMP
This will returns the system date, including fractional seconds and time zone of the
database.
Ex:
SQL> select systimestamp from dual;
SYSTIMESTAMP
---------------------------------------------------------------------------
24-DEC-06 03.49.31.830099 AM +05:30
e) LOCALTIMESTAMP
This will returns local timestamp in the active time zone information, with no time zone
information shown.
Ex:
SQL> select localtimestamp from dual;
LOCALTIMESTAMP
---------------------------------------------------------------------------

ORACLE
24-DEC-06 03.44.18.502874 AM
f) DBTIMEZONE
This will returns the current database time zone in UTC format. (Coordinated Universal
Time)
Ex:
SQL> select dbtimezone from dual;
DBTIMEZONE
---------------
-07:00
g) SESSIONTIMEZONE
This will returns the value of the current session’s time zone.
Ex:
SQL> select sessiontimezone from dual;
SESSIONTIMEZONE
---------------------------------------------------------------------------
+05:30
h) TO_CHAR
This will be used to extract various date formats.
The available date formats as follows.
Syntax: to_char (date, format)
DATE FORMATS
D -- No of days in week
DD -- No of days in month
DDD -- No of days in year
MM -- No of month
MON -- Three letter abbreviation of month
MONTH -- Fully spelled out month

ORACLE
RM -- Roman numeral month
DY -- Three letter abbreviated day
DAY -- Fully spelled out day
Y -- Last one digit of the year
YY -- Last two digits of the year
YYY -- Last three digits of the year
YYYY -- Full four digit year
SYYYY -- Signed year
I -- One digit year from ISO standard
IY -- Two digit year from ISO standard
IYY -- Three digit year from ISO standard
IYYY -- Four digit year from ISO standard
Y, YYY -- Year with comma
YEAR -- Fully spelled out year
CC -- Century
Q -- No of quarters
W -- No of weeks in month
WW -- No of weeks in year
IW -- No of weeks in year from ISO standard
HH -- Hours
MI -- Minutes
SS -- Seconds
FF -- Fractional seconds
AM or PM -- Displays AM or PM depending upon time of day
A.M or P.M -- Displays A.M or P.M depending upon time of day
AD or BC -- Displays AD or BC depending upon the date
A.D or B.C -- Displays AD or BC depending upon the date
FM -- Prefix to month or day, suppresses padding of month or day
TH -- Suffix to a number
SP -- suffix to a number to be spelled out
SPTH -- Suffix combination of TH and SP to be both spelled out
THSP -- same as SPTH
Ex:
SQL> select to_char(sysdate,'dd month yyyy hh:mi:ss am dy') from dual;
TO_CHAR(SYSDATE,'DD MONTH YYYYHH:MI
----------------------------------------------------

ORACLE
24 december 2006 02:03:23 pm sun
SQL> select to_char(sysdate,'dd month year') from dual;
TO_CHAR(SYSDATE,'DDMONTHYEAR')
-------------------------------------------------------
24 december two thousand six
SQL> select to_char(sysdate,'dd fmmonth year') from dual;
TO_CHAR(SYSDATE,'DD FMMONTH YEAR')
-------------------------------------------------------
24 december two thousand six
SQL> select to_char(sysdate,'ddth DDTH') from dual;
TO_CHAR(S
------------
24th 24TH
SQL> select to_char(sysdate,'ddspth DDSPTH') from dual;
TO_CHAR(SYSDATE,'DDSPTHDDSPTH
------------------------------------------
twenty-fourth TWENTY-FOURTH
SQL> select to_char(sysdate,'ddsp Ddsp DDSP ') from dual;
TO_CHAR(SYSDATE,'DDSPDDSPDDSP')
------------------------------------------------
twenty-four Twenty-Four TWENTY-FOUR
i) TO_DATE
This will be used to convert the string into date format.

ORACLE
Syntax: to_date (date)
Ex:
SQL> select to_char(to_date('24/dec/2006','dd/mon/yyyy'), 'dd * month * day') from
dual;
TO_CHAR(TO_DATE('24/DEC/20
--------------------------
24 * december * Sunday
-- If you are not using to_char oracle will display output in default date format.
j) ADD_MONTHS
This will add the specified months to the given date.
Syntax: add_months (date, no_of_months)
Ex:
SQL> select add_months(to_date('11-jan-1990','dd-mon-yyyy'), 5) from dual;
ADD_MONTHS
----------------
11-JUN-90
SQL> select add_months(to_date('11-jan-1990','dd-mon-yyyy'), -5) from dual;
ADD_MONTH
---------------
11-AUG-89
 If no_of_months is zero then it will display the same date.
 If no_of_months is null then it will display nothing.
k) MONTHS_BETWEEN
This will give difference of months between two dates.

ORACLE
Syntax: months_between (date1, date2)
Ex:
SQL> select months_between(to_date('11-aug-1990','dd-mon-yyyy'), to_date('11-jan-
1990','dd-mon-yyyy')) from dual;
MONTHS_BETWEEN(TO_DATE('11-AUG-1990','DD-MON-YYYY'),TO_DATE('11-JAN-
1990','DD-MON-YYYY'))
-----------------------------------------------------------------------------------------------
7
SQL> select months_between(to_date('11-jan-1990','dd-mon-yyyy'), to_date('11-aug-
1990','dd-mon-yyyy')) from dual;
MONTHS_BETWEEN(TO_DATE('11-JAN-1990','DD-MON-YYYY'),TO_DATE('11-AUG-
1990','DD-MON-YYYY'))
-------------------------------------------------------------------------------------------------
-7
l) NEXT_DAY
This will produce next day of the given day from the specified date.
Syntax: next_day (date, day)
Ex:
SQL> select next_day(to_date('24-dec-2006','dd-mon-yyyy'),'sun') from dual;
NEXT_DAY(
-------------
31-DEC-06
-- If the day parameter is null then it will display nothing.
m) LAST_DAY
This will produce last day of the given date.
Syntax: last_day (date)

ORACLE
Ex:
SQL> select last_day(to_date('24-dec-2006','dd-mon-yyyy'),'sun') from dual;
LAST_DAY(
-------------
31-DEC-06
n) EXTRACT
This is used to extract a portion of the date value.
Syntax: extract ((year | month | day | hour | minute | second), date)
Ex:
SQL> select extract(year from sysdate) from dual;
EXTRACT(YEARFROMSYSDATE)
------------------------------------
2006
-- You can extract only one value at a time.
o) GREATEST
This will give the greatest date.
Syntax: greatest (date1, date2, date3 … daten)
Ex:
SQL> select greatest(to_date('11-jan-90','dd-mon-yy'),to_date('11-mar-90','dd-mon-
yy'),to_date('11-apr-90','dd-mon-yy')) from dual;
GREATEST(
-------------
11-APR-90

ORACLE
p) LEAST
This will give the least date.
Syntax: least (date1, date2, date3 … daten)
Ex:
SQL> select least(to_date('11-jan-90','dd-mon-yy'),to_date('11-mar-90','dd-mon-
yy'),to_date('11-apr-90','dd-mon-yy')) from dual;
LEAST(
-------------
11-JAN-90
q) ROUND
Round will rounds the date to which it was equal to or greater than the given date.
Syntax: round (date, (day | month | year))
If the second parameter was year then round will checks the month of the given date in
the
following ranges.
JAN -- JUN
JUL -- DEC
If the month falls between JAN and JUN then it returns the first day of the current year.
If the month falls between JUL and DEC then it returns the first day of the next year.
If the second parameter was month then round will checks the day of the given date in
the
following ranges.
1 -- 15
16 -- 31
If the day falls between 1 and 15 then it returns the first day of the current month.

ORACLE
If the day falls between 16 and 31 then it returns the first day of the next month.
If the second parameter was day then round will checks the week day of the given date in
the following ranges.
SUN -- WED
THU -- SUN
If the week day falls between SUN and WED then it returns the previous sunday.
If the weekday falls between THU and SUN then it returns the next sunday.
 If the second parameter was null then it returns nothing.
 If the you are not specifying the second parameter then round will resets the time to
the
begining of the current day in case of user specified date.
 If the you are not specifying the second parameter then round will resets the time to
the
begining of the next day in case of sysdate.
Ex:
SQL> select round(to_date('24-dec-04','dd-mon-yy'),'year'), round(to_date('11-mar-
06','dd-mon-yy'),'year') from dual;
ROUND(TO_ ROUND(TO_
------------ ---------------
01-JAN-05 01-JAN-06
SQL> select round(to_date('11-jan-04','dd-mon-yy'),'month'), round(to_date('18-jan-
04','dd-mon-yy'),'month') from dual;
ROUND(TO_ ROUND(TO_
------------- ---------------
01-JAN-04 01-FEB-04
SQL> select round(to_date('26-dec-06','dd-mon-yy'),'day'), round(to_date('29-dec-
06','dd-mon-yy'),'day') from dual;
ROUND(TO_ ROUND(TO_
-------------- --------------
24-DEC-06 31-DEC-06

ORACLE
SQL> select to_char(round(to_date('24-dec-06','dd-mon-yy')), 'dd mon yyyy hh:mi:ss
am')
from dual;
TO_CHAR(ROUND(TO_DATE('
---------------------------------
24 dec 2006 12:00:00 am
r) TRUNC
Trunc will chops off the date to which it was equal to or less than the given date.
Syntax: trunc (date, (day | month | year))
 If the second parameter was year then it always returns the first day of the current
year.
 If the second parameter was month then it always returns the first day of the current
month.
 If the second parameter was day then it always returns the previous sunday.
 If the second parameter was null then it returns nothing.
 If the you are not specifying the second parameter then trunk will resets the time to
the
begining of the current day.
Ex:
SQL> select trunc(to_date('24-dec-04','dd-mon-yy'),'year'), trunc(to_date('11-mar-
06','dd-mon-yy'),'year') from dual;
TRUNC(TO_ TRUNC(TO_
------------- --------------
01-JAN-04 01-JAN-06
SQL> select trunc(to_date('11-jan-04','dd-mon-yy'),'month'), trunc(to_date('18-jan-
04','dd-mon-yy'),'month') from dual;
TRUNC(TO_ TRUNC(TO_
------------- -------------
01-JAN-04 01-JAN-04

ORACLE
SQL> select trunc(to_date('26-dec-06','dd-mon-yy'),'day'), trunc(to_date('29-dec-
06','dd-
mon-yy'),'day') from dual;
TRUNC(TO_ TRUNC(TO_
------------- --------------
24-DEC-06 24-DEC-06
SQL> select to_char(trunc(to_date('24-dec-06','dd-mon-yy')), 'dd mon yyyy hh:mi:ss
am')
from dual;
TO_CHAR(TRUNC(TO_DATE('
---------------------------------
24 dec 2006 12:00:00 am
s) NEW_TIME
This will give the desired timezone’s date and time.
Syntax: new_time (date, current_timezone, desired_timezone)
Available timezones are as follows.
TIMEZONES
AST/ADT -- Atlantic standard/day light time
BST/BDT -- Bering standard/day light time
CST/CDT -- Central standard/day light time
EST/EDT -- Eastern standard/day light time
GMT -- Greenwich mean time
HST/HDT -- Alaska-Hawaii standard/day light time
MST/MDT -- Mountain standard/day light time
NST -- Newfoundland standard time
PST/PDT -- Pacific standard/day light time
YST/YDT -- Yukon standard/day light time
Ex:

ORACLE
SQL> select to_char(new_time(sysdate,'gmt','yst'),'dd mon yyyy hh:mi:ss am') from
dual;
TO_CHAR(NEW_TIME(SYSDAT
-----------------------------------
24 dec 2006 02:51:20 pm
SQL> select to_char(new_time(sysdate,'gmt','est'),'dd mon yyyy hh:mi:ss am') from
dual;
TO_CHAR(NEW_TIME(SYSDAT
-----------------------
24 dec 2006 06:51:26 pm
t) COALESCE
This will give the first non-null date.
Syntax: coalesce (date1, date2, date3 … daten)
Ex:
SQL> select coalesce('12-jan-90','13-jan-99'), coalesce(null,'12-jan-90','23-mar-
98',null)
from dual;
COALESCE( COALESCE(
------------- ------------
12-jan-90 12-jan-90
MISCELLANEOUS FUNCTIONS
 Uid
 User
 Vsize
 Rank
 Dense_rank
a) UID
This will returns the integer value corresponding to the user currently logged in.

ORACLE
Ex:
SQL> select uid from dual;
UID
----------
319
b) USER
This will returns the login’s user name.
Ex:
SQL> select user from dual;
USER
----------------
SAKETH
c) VSIZE
This will returns the number of bytes in the expression.
Ex:
SQL> select vsize(123), vsize('computer'), vsize('12-jan-90') from dual;
VSIZE(123) VSIZE('COMPUTER') VSIZE('12-JAN-90')
------------- ----------------------- ----------------------
3 8 9
d) RANK
This will give the non-sequential ranking.
Ex:
SQL> select rownum,sal from (select sal from emp order by sal desc);
ROWNUM SAL
---------- ----------

ORACLE
1 5000
2 3000
3 3000
4 2975
5 2850
6 2450
7 1600
8 1500
9 1300
10 1250
11 1250
12 1100
13 1000
14 950
15 800
SQL> select rank(2975) within group(order by sal desc) from emp;
RANK(2975)WITHINGROUP(ORDERBYSALDESC)
---------------------------------------------------------
4
d) DENSE_RANK
This will give the sequential ranking.
Ex:
SQL> select dense_rank(2975) within group(order by sal desc) from emp;
DENSE_RANK(2975)WITHINGROUP(ORDERBYSALDESC)
-----------------------------------------------------------------
3
CONVERSION FUNCTIONS
 Bin_to_num
 Chartorowid
 Rowidtochar
 To_number
 To_char

ORACLE
 To_date
a) BIN_TO_NUM
This will convert the binary value to its numerical equivalent.
Syntax: bin_to_num( binary_bits)
Ex:
SQL> select bin_to_num(1,1,0) from dual;
BIN_TO_NUM(1,1,0)
------------------------
6
 If all the bits are zero then it produces zero.
 If all the bits are null then it produces an error.
b) CHARTOROWID
This will convert a character string to act like an internal oracle row identifier or rowid.
c) ROWIDTOCHAR
This will convert an internal oracle row identifier or rowid to character string.
d) TO_NUMBER
This will convert a char or varchar to number.
e) TO_CHAR
This will convert a number or date to character string.
f) TO_DATE
This will convert a number, char or varchar to a date.
GROUP FUNCTIONS

ORACLE
 Sum
 Avg
 Max
 Min
 Count
Group functions will be applied on all the rows but produces single output.
a) SUM
This will give the sum of the values of the specified column.
Syntax: sum (column)
Ex:
SQL> select sum(sal) from emp;
SUM(SAL)
----------
38600
b) AVG
This will give the average of the values of the specified column.
Syntax: avg (column)
Ex:
SQL> select avg(sal) from emp;
AVG(SAL)
---------------
2757.14286
c) MAX
This will give the maximum of the values of the specified column.
Syntax: max (column)

ORACLE
Ex:
SQL> select max(sal) from emp;
MAX(SAL)
----------
5000
d) MIN
This will give the minimum of the values of the specified column.
Syntax: min (column)
Ex:
SQL> select min(sal) from emp;
MIN(SAL)
----------
500
e) COUNT
This will give the count of the values of the specified column.
Syntax: count (column)
Ex:
SQL> select count(sal),count(*) from emp;
COUNT(SAL) COUNT(*)
-------------- ------------
14 14

ORACLE
CONSTRAINTS
Constraints are categorized as follows.
Domain integrity constraints
 Not null
 Check
Entity integrity constraints
 Unique
 Primary key
Referential integrity constraints
 Foreign key
Constraints are always attached to a column not a table.
We can add constraints in three ways.
 Column level -- along with the column definition
 Table level -- after the table definition
 Alter level -- using alter command
While adding constraints you need not specify the name but the type only, oracle will
internally name the constraint.
If you want to give a name to the constraint, you have to use the constraint clause.
NOT NULL
This is used to avoid null values.
We can add this constraint in column level only.
Ex:
SQL> create table student(no number(2) not null, name varchar(10), marks number(3));
SQL> create table student(no number(2) constraint nn not null, name varchar(10), marks
number(3));
CHECK

ORACLE
This is used to insert the values based on specified condition.
We can add this constraint in all three levels.
Ex:
COLUMN LEVEL
SQL> create table student(no number(2) , name varchar(10), marks number(3) check
(marks > 300));
SQL> create table student(no number(2) , name varchar(10), marks number(3) constraint
ch
check(marks > 300));
TABLE LEVEL
SQL> create table student(no number(2) , name varchar(10), marks number(3), check
(marks > 300));
SQL> create table student(no number(2) , name varchar(10), marks number(3),
constraint
ch check(marks > 300));
ALTER LEVEL
SQL> alter table student add check(marks>300);
SQL> alter table student add constraint ch check(marks>300);
UNIQUE
This is used to avoid duplicates but it allow nulls.
Ex:
COLUMN LEVEL
SQL> create table student(no number(2) unique, name varchar(10), marks number(3));
SQL> create table student(no number(2) constraint un unique, name varchar(10), marks
number(3));
TABLE LEVEL

ORACLE
unique(no));
constraint
un unique(no));
ALTER LEVEL
SQL> alter table student add unique(no);
SQL> alter table student add constraint un unique(no);
PRIMARY KEY
This is used to avoid duplicates and nulls. This will work as combination of unique and not
null.
Primary key always attached to the parent table.
Ex:
COLUMN LEVEL
SQL> create table student(no number(2) primary key, name varchar(10), marks
number(3));
SQL> create table student(no number(2) constraint pk primary key, name varchar(10),
marks number(3));
TABLE LEVEL
primary key(no));
constraint
pk primary key(no));
ALTER LEVEL
SQL> alter table student add primary key(no);
SQL> alter table student add constraint pk primary key(no);
FOREIGN KEY

ORACLE
This is used to reference the parent table primary key column which allows duplicates.
Foreign key always attached to the child table.
We can add this constraint in table and alter levels only.
Ex:
TABLE LEVEL
SQL> create table emp(empno number(2), ename varchar(10), deptno number(2),
primary key(empno), foreign key(deptno) references dept(deptno));
constraint pk primary key(empno), constraint fk foreign key(deptno) references
dept(deptno));
ALTER LEVEL
SQL> alter table emp add foreign key(deptno) references dept(deptno);
SQL> alter table emp add constraint fk foreign key(deptno) references dept(deptno);
Once the primary key and foreign key relationship has been created then you can not
remove any parent record if the dependent childs exists.
USING ON DELTE CASCADE
By using this clause you can remove the parent record even it childs exists.
Because when ever you remove parent record oracle automatically removes all its
dependent records from child table, if this clause is present while creating foreign key
constraint.
Ex:
TABLE LEVEL
primary key(empno), foreign key(deptno) references dept(deptno) on delete
cascade);
constraint pk primary key(empno), constraint fk foreign key(deptno) references
dept(deptno) on delete cascade);
ALTER LEVEL

ORACLE
SQL> alter table emp add foreign key(deptno) references dept(deptno) on delete cascade;
SQL> alter table emp add constraint fk foreign key(deptno) references dept(deptno) on
delete cascade;
COMPOSITE KEYS
A composite key can be defined on a combination of columns.
We can define composite keys on entity integrity and referential integrity constraints.
Composite key can be defined in table and alter levels only.
Ex:
UNIQUE (TABLE LEVEL)
unique(no,name));
constraint
un unique(no,name));
UNIQUE (ALTER LEVEL)
SQL> alter table student add unique(no,name);
SQL> alter table student add constraint un unique(no,name);
PRIMARY KEY (TABLE LEVEL)
primary key(no,name));
constraint
pk primary key(no,name));
PRIMARY KEY (ALTER LEVEL)
SQL> alter table student add primary key(no,anme);
SQL> alter table student add constraint pk primary key(no,name);
FOREIGN KEY (TABLE LEVEL)
SQL> create table emp(empno number(2), ename varchar(10), deptno number(2), dname

ORACLE
varchar(10), primary key(empno), foreign key(deptno,dname) references
dept(deptno,dname));
SQL> create table emp(empno number(2), ename varchar(10), deptno number(2), dname
varchar(10), constraint pk primary key(empno), constraint fk foreign
key(deptno,dname) references dept(deptno,dname));
FOREIGN KEY (ALTER LEVEL)
SQL> alter table emp add foreign key(deptno,dname) references dept(deptno,dname);
SQL> alter table emp add constraint fk foreign key(deptno,dname) references
dept(deptno,dname);
DEFERRABLE CONSTRAINTS
Each constraint has two additional attributes to support deferred checking of constraints.
 Deferred initially immediate
 Deferred initially deferred
Deferred initially immediate checks for constraint violation at the time of insert.
Deferred initially deferred checks for constraint violation at the time of commit.
Ex:
SQL> create table student(no number(2), name varchar(10), marks number(3), constraint
un unique(no) deferred initially immediate);
SQL> create table student(no number(2), name varchar(10), marks number(3), constraint
un unique(no) deferred initially deferred);
SQL> alter table student add constraint un unique(no) deferrable initially deferred;
SQL> set constraints all immediate;
This will enable all the constraints violations at the time of inserting.
SQL> set constraints all deferred;
This will enable all the constraints violations at the time of commit.
OPERATIONS WITH CONSTRAINTS

ORACLE
Possible operations with constraints as follows.
 Enable
 Disable
 Enforce
 Drop
ENABLE
This will enable the constraint. Before enable, the constraint will check the existing data.
Ex:
SQL> alter table student enable constraint un;
DISABLE
This will disable the constraint.
Ex:
SQL> alter table student enable constraint un;
ENFORCE
This will enforce the constraint rather than enable for future inserts or updates.
This will not check for existing data while enforcing data.
Ex:
SQL> alter table student enforce constraint un;
DROP
This will remove the constraint.
Ex:
SQL> alter table student drop constraint un;
Once the table is dropped, constraints automatically will drop.

ORACLE
CASE AND DEFAULT
CASE
Case is similar to decode but easier to understand while going through coding
Ex:
SQL> Select sal,
Case sal
When 500 then ‘low’
When 5000 then ‘high’
Else ‘medium’
End case
From emp;
SAL CASE
----- --------
500 low
2500 medium
2000 medium
3500 medium
3000 medium
5000 high
4000 medium
5000 high
1800 medium
1200 medium
2000 medium
2700 medium
2200 medium
3200 medium
DEFAULT

ORACLE
Default can be considered as a substitute behavior of not null constraint when applied to
new rows being entered into the table.
When you define a column with the default keyword followed by a value, you are actually
telling the database that, on insert if a row was not assigned a value for this column, use the
default value that you have specified.
Default is applied only during insertion of new rows.
Ex:
SQL> create table student(no number(2) default 11,name varchar(2));
SQL> insert into student values(1,'a');
SQL> insert into student(name) values('b');
NO NAME
------ ---------
1 a
11 b
SQL> insert into student values(null, ‘c’);
NO NAME
------ ---------
1 a
11 b
C
-- Default can not override nulls.

ORACLE
ABSTRACT DATA TYPES
Some times you may want type which holds all types of data including numbers, chars and
special characters something like this. You can not achieve this using pre-defined types.
You can define custom types which holds your desired data.
Ex:
Suppose in a table we have address column which holds hno and city information.
We will define a custom type which holds both numeric as well as char data.
CREATING ADT
SQL> create type addr as object(hno number(3),city varchar(10)); /
CREATING TABLE BASED ON ADT
SQL> create table student(no number(2),name varchar(2),address addr);
INSERTING DATA INTO ADT TABLES
SQL> insert into student values(1,'a',addr(111,'hyd'));
SQL> insert into student values(2,'b',addr(222,'bang'));
SQL> insert into student values(3,'c',addr(333,'delhi'));
SELECTING DATA FROM ADT TABLES
NO NAME ADDRESS(HNO, CITY)
--- ------- -------------------------
1 a ADDR(111, 'hyd')
2 b ADDR(222, 'bang')
3 c ADDR(333, 'delhi')
SQL> select no,name,s.address.hno,s.address.city from student s;
NO NAME ADDRESS.HNO ADDRESS.CITY
---- ------- ----------------- ----------------
1 a 111 hyd

ORACLE
2 b 222 bang
3 c 333 delhi
UPDATE WITH ADT TABLES
SQL> update student s set s.address.city = 'bombay' where s.address.hno = 333;
---- ------- ----------------- ----------------
1 a 111 hyd
2 b 222 bang
3 c 333 bombay
DELETE WITH ADT TABLES
SQL> delete student s where s.address.hno = 111;
---- ------- ----------------- ----------------
2 b 222 bang
3 c 333 bombay
DROPPING ADT
SQL> drop type addr;

ORACLE
OBJECT VIEWS AND METHODS
OBJECT VIEWS
If you want to implement objects with the existing table, object views come into picture.
You define the object and create a view which relates this object to the existing table
nothing but object view.
Object views are used to relate the user defined objects to the existing table.
Ex:
1) Assume that the table student has already been created with the following columns
SQL> create table student(no number(2),name varchar(10),hno number(3),city
varchar(10));
2) Create the following types
SQL> create type addr as object(hno number(2),city varchar(10));/
SQL> create type stud as object(name varchar(10),address addr);/
3) Relate the objects to the student table by creating the object view
SQL> create view student_ov(no,stud_info) as select no,stud(name,addr(hno,city))
from
student;
4) Now you can insert data into student table in two ways
a) By regular insert
SQL> Insert into student values(1,’sudha’,111,’hyd’);
b) By using object view
SQL> Insert into student_ov values(1,stud(‘sudha’,addr(111,’hyd’)));
METHODS
You can define methods which are nothing but functions in types and apply in the tables
which holds the types;
Ex:
1) Defining methods in types
SQL> Create type stud as object(name varchar(10),marks number(3),
Member function makrs_f(marks in number) return number,
Pragma restrict_references(marks_f,wnds,rnds,wnps,fnps));/
2) Defining type body

ORACLE
SQL> Create type body stud as
Member function marks_f(marks in number) return number is
Begin
Return (marks+100);
End marks_f;
End;/
3) Create a table using stud type
SQL> Create table student(no number(2),info stud);
4) Insert some data into student table
SQL> Insert into student values(1,stud(‘sudha’,100));
5) Using method in select
SQL> Select s.info.marks_f(s.info.marks) from student s;
-- Here we are using the pragma restrict_references to avoid the writes to the database.

ORACLE
VARRAYS AND NESTED TABLES
VARRAYS
A varying array allows you to store repeating attributes of a record in a single row but with
limit.
Ex:
1) We can create varrays using oracle types as well as user defined types.
a) Varray using pre-defined types
SQL> Create type va as varray(5) of varchar(10);/
b) Varrays using user defined types
SQL> Create type addr as object(hno number(3),city varchar(10));/
SQL> Create type va as varray(5) of addr;/
2) Using varray in table
SQL> Create table student(no number(2),name varchar(10),address va);
3) Inserting values into varray table
SQL> Insert into student values(1,’sudha’,va(addr(111,’hyd’)));
SQL> Insert into student values(2,’jagan’,va(addr(111,’hyd’),addr(222,’bang’)));
4) Selecting data from varray table
SQL> Select * from student;
-- This will display varray column data along with varray and adt;
SQL> Select no,name, s.* from student s1, table(s1.address) s;
-- This will display in general format
5) Instead of s.* you can specify the columns in varray
SQL> Select no,name, s.hno,s.city from student s1,table(s1.address) s;
-- Update and delete not possible in varrays.
-- Here we used table function which will take the varray column as input for producing
output excluding varray and types.
NESTED TABLES
A nested table is, as its name implies, a table within a table. In this case it is a table that is
represented as a column within another table.
Nested table has the same effect of varrays but has no limit.
Ex:

ORACLE
1) We can create nested tables using oracle types and user defined types which has no
limit
a) Nested tables using pre-defined types
SQL> Create type nt as table of varchar(10);/
b) Nested tables using user defined types
SQL> Create type addr as object(hno number(3),city varchar(10));/
SQL> Create type nt as table of addr;/
2) Using nested table in table
SQL> Create table student(no number(2),name varchar(10),address nt) nested table
address store as student_temp;
3) Inserting values into table which has nested table
SQL> Insert into student values (1,’sudha’,nt(addr(111,’hyd’)));
SQL> Insert into student values (2,’jagan’,nt(addr(111,’hyd’),addr(222,’bang’)));
4) Selecting data from table which has nested table
SQL> Select * from student;
-- This will display nested table column data along with nested table and adt;
SQL> Select no,name, s.* from student s1, table(s1.address) s;
-- This will display in general format
5) Instead of s.* you can specify the columns in nested table
SQL> Select no,name, s.hno,s.city from student s1,table(s1.address) s;
6) Inserting nested table data to the existing row
SQL> Insert into table(select address from student where no=1)
values(addr(555,’chennai’));
7) Update in nested tables
SQL> Update table(select address from student where no=2) s set s.city=’bombay’
where
s.hno = 222;
8) Delete in nested table
SQL> Delete table(select address from student where no=3) s where s.hno=333;
DATA MODEL
 ALL_COLL_TYPES
 ALL_TYPES
 DBA_COLL_TYPES
 DBA_TYPES
 USER_COLL_TYPES
 USER_TYPES

ORACLE
FLASHBACK QUERY
Used to retrieve the data which has been already committed with out going for recovery.
Flashbacks are of two types
 Time base flashback
 SCN based flashback (SCN stands for System Change Number)
Ex:
1) Using time based flashback
a) SQL> Select *from student;
-- This will display all the rows
b) SQL> Delete student;
c) SQL> Commit; -- this will commit the work.
d) SQL> Select *from student;
-- Here it will display nothing
e) Then execute the following procedures
SQL> Exec dbms_flashback.enable_at_time(sysdate-2/1440)
f) SQL> Select *from student;
-- Here it will display the lost data
-- The lost data will come but the current system time was used
g) SQL> Exec dbms_flashback.disable
-- Here we have to disable the flashback to enable it again
2) Using SCN based flashback
a) Declare a variable to store SCN
SQL> Variable s number
b) Get the SCN
SQL> Exec :s := exec dbms_flashback.get_system_change_number
c) To see the SCN
SQL> Print s
d) Then execute the following procedures
SQL> Exec dbms_flashback.enable_at_system_change_number(:s)
SQL> Exec dbms_flashback.disable

ORACLE
EXTERNAL TABLES
You can user external table feature to access external files as if they are tables inside the
database.
When you create an external table, you define its structure and location with in oracle.
When you query the table, oracle reads the external table and returns the results just as if
the data had been stored with in the database.
ACCESSING EXTERNAL TABLE DATA
To access external files from within oracle, you must first use the create directory command
to define a directory object pointing to the external file location
Users who will access the external files must have the read and write privilege on the
directory.
Ex:
CREATING DIRECTORY AND OS LEVEL FILE
SQL> Sqlplus system/manager
SQL> Create directory saketh_dir as ‘/Visdb/visdb/9.2.0/external’;
SQL> Grant all on directory saketh_dir to saketh;
SQL> Conn saketh/saketh
SQL> Spool dept.lst
SQL> Select deptno || ‘,’ || dname || ‘,’ || loc from dept;
SQL> Spool off
CREATING EXTERNAL TABLE
SQL> Create table dept_ext
(deptno number(2),
Dname varchar(14),
Loc varchar(13))
Organization external ( type oracle_loader
Default directory saketh_dir
Access parameters
( records delimited by newline
Fields terminated by “,”
( deptno number(2),

ORACLE
Dname varchar(14),
Loc varchar(13)))
Location (‘/Visdb/visdb/9.2.0/dept.lst’));
SELECTING DATA FROM EXTERNAL TABLE
SQL> select * from dept_ext;
This will read from dept.lst which is a operating system level file.
LIMITATIONS ON EXTERNAL TABLES
a) You can not perform insert, update, and delete operations
a) Indexing not possible
b) Constraints not possible
BENEFITS OF EXTERNAL TABLES
a) Queries of external tables complete very quickly even though a full table scan id
required with each access
b) You can join external tables to each other or to standard tables
REF DEREF VALUE
REF
 The ref function allows referencing of existing row objects.
 Each of the row objects has an object id value assigned to it.
 The object id assigned can be seen by using ref function.
DEREF
 The deref function performs opposite action.
 It takes a reference value of object id and returns the value of the row objects.
VALUE
 Even though the primary table is object table, still it displays the rows in general
format.
 To display the entire structure of the object, this will be used.

ORACLE
Ex:
1) create vendot_adt type
SQL> Create type vendor_adt as object (vendor_code number(2), vendor_name
varchar(2), vendor_address varchar(10));/
2) create object tables vendors and vendors1
SQL> Create table vendors of vendor_adt;
SQL> Create table vendors1 of vendor_adt;
3) insert the data into object tables
SQL> insert into vendors values(1, ‘a’, ‘hyd’);
SQL> insert into vendors values(2, ‘b’, ‘bang’);
SQL> insert into vendors1 values(3, ‘c’, ‘delhi’);
SQL> insert into vendors1 values(4, ‘d’, ‘chennai’);
4) create another table orders which holds the vendor_adt type also.
SQL> Create table orders (order_no number(2), vendor_info ref vendor_adt);
Or
SQL> Create table orders (order_no number(2), vendor_info ref vendor_adt with
rowid);
5) insert the data into orders table
The vendor_info column in the following syntaxes will store object id of any table
which
is referenced by vendor_adt object ( both vendors and vendors1).
SQL> insert into orders values(11,(select ref(v) from vendors v where vendor_code =
1));
SQL> insert into orders values(12,(select ref(v) from vendors v where vendor_code =
2));
SQL> insert into orders values(13,(select ref(v1) from vendors1 v1 where vendor_code
=
1));
SQL> insert into orders values(14,(select ref(v1) from vendors1 v1 where vendor_code
=
1));
6) To see the object ids of vendor table
SQL> Select ref(V) from vendors v;
7) If you see the vendor_info of orders it will show only the object ids not the values, to
see
the values

ORACLE
SQL> Select deref(o.vendor_info) from orders o;
8) Even though the vendors table is object table it will not show the adt along with data,
to
see the data along with the adt
SQL>Select * from vendors;
This will give the data without adt.
SQL>Select value(v) from vendors v;
This will give the columns data along wih the type.
REF CONSTRAINTS
Ref can also acts as constraint.
Even though vendors1 also holding vendor_adt, the orders table will store the object ids of
vendors only because it is constrained to that table only.
The vendor_info column in the following syntaxes will store object ids of vendors only.
SQL> Create table orders (order_no number(2), vendor_info ref vendor_adt scope is
vendors);
Or
SQL> Create table orders (order_no number(2), vendor_info ref vendor_adt constraint fk
references vendors);
OBJECT VIEWS WITH REFERENCES
To implement the objects and the ref constraints to the existing tables, what we can do?
Simply drop the both tables and recreate with objects and ref constrains.
But you can achieve this with out dropping the tables and without losing the data by
creating object views with references.
Ex:
a) Create the following tables
SQL> Create table student1(no number(2) primary key,name varchar(2),marks
number(3));
SQL> Create table student2(no number(2) primary key,hno number(3),city
varchar(10),id
number(2),foreign Key(id) references student1(no));

ORACLE
b) Insert the records into both tables
SQL> insert into student1(1,’a’,100);
SQL> insert into student1(2,’b’,200);
SQL> insert into student2(11,111,’hyd’,1);
SQL> insert into student2(12,222,’bang’,2);
SQL> insert into student2(13,333,’bombay’,1);
c) Create the type
SQL> create or replace type stud as object(no number(2),name varchar(2),marks
number(3));/
d) Generating OIDs
SQL> Create or replace view student1_ov of stud with object identifier(or id) (no) as
Select * from Student1;
e) Generating references
SQL> Create or replace view student2_ov as select
no,hno,city,make_ref(student1_ov,id)
id from Student2;
d) Query the following
SQL> select *from student1_ov;
SQL> select ref(s) from student1_ov s;
SQL> select values(s) from student1_ov;
SQ> select *from student2_ov;
SQL> select deref(s.id) from student2_ov s;
PARTITIONS
A single logical table can be split into a number of physically separate pieces based on
ranges of key values. Each of the parts of the table is called a partition.
A non-partitioned table can not be partitioned later.
TYPES
 Range partitions
 List partitions
 Hash partitions
 Sub partitions

ORACLE
ADVANTAGES
 Reducing downtime for scheduled maintenance, which allows maintenance operations
to be carried out on selected partitions while other partitions are available to users.
 Reducing downtime due to data failure, failure of a particular partition will no way
affect other partitions.
 Partition independence allows for concurrent use of the various partitions for various
purposes.
ADVANTAGES OF PARTITIONS BY STORING THEM IN DIFFERENT TABLESPACES
 Reduces the possibility of data corruption in multiple partitions.
 Back up and recovery of each partition can be done independently.
DISADVANTAGES
 Partitioned tables cannot contain any columns with long or long raw datatypes, LOB
types or object types.
RANGE PARTITIONS
a) Creating range partitioned table
SQL> Create table student(no number(2),name varchar(2)) partition by range(no)
(partition
p1 values less than(10), partition p2 values less than(20), partition p3 values less
than(30),partition p4 values less than(maxvalue));
** if you are using maxvalue for the last partition, you can not add a partition.
b) Inserting records into range partitioned table
SQL> Insert into student values(1,’a’); -- this will go to p1
SQL> Insert into student values(11,’b’); -- this will go to p2
SQL> Insert into student values(21,’c’); -- this will go to p3
SQL> Insert into student values(31,’d’); -- this will go to p4
c) Retrieving records from range partitioned table
SQL> Select *from student;

ORACLE
SQL> Select *from student partition(p1);
d) Possible operations with range partitions
 Add
 Drop
 Truncate
 Rename
 Split
 Move
 Exchange
e) Adding a partition
SQL> Alter table student add partition p5 values less than(40);
f) Dropping a partition
SQL> Alter table student drop partition p4;
g) Renaming a partition
SQL> Alter table student rename partition p3 to p6;
h) Truncate a partition
SQL> Alter table student truncate partition p6;
i) Splitting a partition
SQL> Alter table student split partition p2 at(15) into (partition p21,partition p22);
j) Exchanging a partition
SQL> Alter table student exchange partition p1 with table student2;
k) Moving a partition
SQL> Alter table student move partition p21 tablespace saketh_ts;
LIST PARTITIONS
a) Creating list partitioned table
SQL> Create table student(no number(2),name varchar(2)) partition by list(no) (partition
p1
values(1,2,3,4,5), partition p2 values(6,7,8,9,10),partition p3
values(11,12,13,14,15),
partition p4 values(16,17,18,19,20));
b) Inserting records into list partitioned table
SQL> Insert into student values(11,’c’); -- this will go to p3
SQL> Insert into student values(16,’d’); -- this will go to p4
c) Retrieving records from list partitioned table

ORACLE
d) Possible operations with list partitions
 Add
 Drop
 Truncate
 Rename
 Move
 Exchange
SQL> Alter table student add partition p5 values(21,22,23,24,25);
i) Exchanging a partition
SQL> Alter table student exchange partition p1 with table student2;
j) Moving a partition
SQL> Alter table student move partition p2 tablespace saketh_ts;
HASH PARTITIONS
a) Creating hash partitioned table
SQL> Create table student(no number(2),name varchar(2)) partition by hash(no)
partitions
5;
Here oracle automatically gives partition names like
SYS_P1
SYS_P2
SYS_P3
SYS_P4
SYS_P5
b) Inserting records into hash partitioned table
it will insert the records based on hash function calculated by taking the partition key
SQL> Insert into student values(1,’a’);
SQL> Insert into student values(6,’b’);

ORACLE
SQL> Insert into student values(11,’c’);
SQL> Insert into student values(16,’d’);
c) Retrieving records from hash partitioned table
SQL> Select *from student partition(sys_p1);
d) Possible operations with hash partitions
 Add
 Truncate
 Rename
 Move
 Exchange
SQL> Alter table student add partition p6 ;
f) Renaming a partition
g) Truncate a partition
h) Exchanging a partition
SQL> Alter table student exchange partition sys_p1 with table student2;
i) Moving a partition
SQL> Alter table student move partition sys_p2 tablespace saketh_ts;
SUB-PARTITIONS WITH RANGE AND HASH
Subpartitions clause is used by hash only. We can not create subpartitions with list and hash
partitions.
a) Creating subpartitioned table
SQL> Create table student(no number(2),name varchar(2),marks number(3))
Partition by range(no) subpartition by hash(name) subpartitions 3
(Partition p1 values less than(10),partition p2 values less than(20));
This will create two partitions p1 and p2 with three subpartitions for each partition
P1 – SYS_SUBP1
SYS_SUBP2
SYS_SUBP3
P2 – SYS_SUBP4
SYS_SUBP5

ORACLE
SYS_SUBP6
** if you are using maxvalue for the last partition, you can not add a partition.
b) Inserting records into subpartitioned table
c) Retrieving records from subpartitioned table
SQL> Select *from student subpartition(sys_subp1);
d) Possible operations with subpartitions
 Add
 Drop
 Truncate
 Rename
 Split
SQL> Alter table student add partition p3 values less than(30);
i) Splitting a partition
SQL> Alter table student split partition p3 at(15) into (partition p31,partition p32);
DATA MODEL
 ALL_IND_PARTITIONS
 ALL_IND_SUBPARTITIONS
 ALL_TAB_PARTITIONS
 ALL_TAB_SUBPARTITIONS
 DBA_IND_PARTITIONS
 DBA_IND_SUBPARTITIONS
 DBA_TAB_PARTITIONS
 DBA_TAB_SUBPARTITIONS
 USER_IND_PARTITIONS
 USER_IND_SUBPARTITIONS

ORACLE
 USER_TAB_PARTITIONS
 USER_TAB_SUBPARTITIONS
GROUP BY AND HAVING
GROUP BY
Using group by, we can create groups of related information.
Columns used in select must be used with group by, otherwise it was not a group by
expression.
Ex:
SQL> select deptno, sum(sal) from emp group by deptno;
DEPTNO SUM(SAL)
---------- ----------
10 8750
20 10875
30 9400
SQL> select deptno,job,sum(sal) from emp group by deptno,job;
DEPTNO JOB SUM(SAL)
---------- --------- ----------
10 CLERK 1300
10 MANAGER 2450
10 PRESIDENT 5000
20 ANALYST 6000
20 CLERK 1900
20 MANAGER 2975
30 CLERK 950
30 MANAGER 2850
30 SALESMAN 5600
HAVING

ORACLE
This will work as where clause which can be used only with group by because of absence of
where clause in group by.
Ex:
SQL> select deptno,job,sum(sal) tsal from emp group by deptno,job having sum(sal) >
3000;
DEPTNO JOB TSAL
---------- --------- ----------
10 PRESIDENT 5000
20 ANALYST 6000
30 SALESMAN 5600
SQL> select deptno,job,sum(sal) tsal from emp group by deptno,job having sum(sal) >
3000
order by job;
DEPTNO JOB TSAL
---------- --------- ----------
20 ANALYST 6000
10 PRESIDENT 5000
30 SALESMAN 5600
ORDER OF EXECUTION
 Group the rows together based on group by clause.
 Calculate the group functions for each group.
 Choose and eliminate the groups based on the having clause.
 Order the groups based on the specified column.

ORACLE
ROLLUP GROUPING CUBE
These are the enhancements to the group by feature.
USING ROLLUP
This will give the salaries in each department in each job category along wih the total salary
fot individual departments and the total salary of all the departments.
SQL> Select deptno,job,sum(sal) from emp group by rollup(deptno,job);
DEPTNO JOB SUM(SAL)
---------- --------- ----------
10 CLERK 1300
10 MANAGER 2450
10 PRESIDENT 5000
10 8750
20 ANALYST 6000
20 CLERK 1900
20 MANAGER 2975
20 10875
30 CLERK 950
30 MANAGER 2850
30 SALESMAN 5600
30 9400
29025
USING GROUPING
In the above query it will give the total salary of the individual departments but with a
blank in the job column and gives the total salary of all the departments with blanks in
deptno and job columns.
To replace these blanks with your desired string grouping will be used
SQL> select decode(grouping(deptno),1,'All Depts',deptno),decode(grouping(job),1,'All
jobs',job),sum(sal) from emp group by rollup(deptno,job);

ORACLE
DECODE(GROUPING(DEPTNO),1,'ALLDEPTS',DEP DECODE(GR SUM(SAL)
----------------------------------- ---------------------------------- --------------
10 CLERK 1300
10 MANAGER 2450
10 PRESIDENT 5000
10 All jobs 8750
20 ANALYST 6000
20 CLERK 1900
20 MANAGER 2975
20 All jobs 10875
30 CLERK 950
30 MANAGER 2850
30 SALESMAN 5600
30 All jobs 9400
All Depts All jobs 29025
Grouping will return 1 if the column which is specified in the grouping function has been
used in rollup.
Grouping will be used in association with decode.
USING CUBE
This will give the salaries in each department in each job category, the total salary for
individual departments, the total salary of all the departments and the salaries in each job
category.
SQL> select decode(grouping(deptno),1,’All Depts’,deptno),decode(grouping(job),1,’All
Jobs’,job),sum(sal) from emp group by cube(deptno,job);
DECODE(GROUPING(DEPTNO),1,'ALLDEPTS',DEP DECODE(GR SUM(SAL)
----------------------------------- ------------------------------------ ------------
10 CLERK 1300
10 MANAGER 2450
10 PRESIDENT 5000
10 All Jobs 8750
20 ANALYST 6000
20 CLERK 1900
20 MANAGER 2975

ORACLE
20 All Jobs 10875
30 CLERK 950
30 MANAGER 2850
30 SALESMAN 5600
30 All Jobs 9400
All Depts ANALYST 6000
All Depts CLERK 4150
All Depts MANAGER 8275
All Depts PRESIDENT 5000
All Depts SALESMAN 5600
All Depts All Jobs 29025
SET OPERATORS
TYPES
 Union
 Union all
 Intersect
 Minus
UNION
This will combine the records of multiple tables having the same structure.
Ex:
SQL> select * from student1 union select * from student2;
UNION ALL
This will combine the records of multiple tables having the same structure but including
duplicates.
Ex:
SQL> select * from student1 union all select * from student2;
INTERSECT

ORACLE
This will give the common records of multiple tables having the same structure.
Ex:
SQL> select * from student1 intersect select * from student2;
MINUS
This will give the records of a table whose records are not in other tables having the same
structure.
Ex:
SQL> select * from student1 minus select * from student2;
VIEWS
A view is a database object that is a logical representation of a table. It is delivered from a
table but has no storage of its own and often may be used in the same manner as a table.
A view takes the output of the query and treats it as a table, therefore a view can be
thought of as a stored query or a virtual table.
TYPES
 Simple view
 Complex view
Simple view can be created from one table where as complex view can be created from
multiple tables.
WHY VIEWS?
 Provides additional level of security by restricting access to a predetermined set of
rows and/or columns of a table.
 Hide the data complexity.
 Simplify commands for the user.
VIEWS WITHOUT DML
 Read only view
 View with group by
 View with aggregate functions

ORACLE
 View with rownum
 Partition view
 View with distinct
Ex:
SQL> Create view dept_v as select *from dept with read only;
SQL> Create view dept_v as select deptno, sum(sal) t_sal from emp group by deptno;
SQL> Create view stud as select rownum no, name, marks from student;
SQL> Create view student as select *from student1 union select *from student2;
SQL> Create view stud as select distinct no,name from student;
VIEWS WITH DML
 View with not null column -- insert with out not null column not possible
-- update not null column to null is not possible
-- delete possible
 View with out not null column which was in base table -- insert not possible
-- update, delete possible
 View with expression -- insert , update not possible
-- delete possible
 View with functions (except aggregate) -- insert, update not possible
-- delete possible
 View was created but the underlying table was dropped then we will get the message
like “ view has errors ”.
 View was created but the base table has been altered but still the view was with the
initial definition, we have to replace the view to affect the changes.
 Complex view (view with more than one table) -- insert not possible
-- update, delete possible (not
always)
CREATING VIEW WITHOUT HAVING THE BASE TABLE
SQL> Create force view stud as select *From student;
-- Once the base table was created then the view is validated.
VIEW WITH CHECK OPTION CONSTRAINT
SQL> Create view stud as select *from student where marks = 500 with check option
constraint
Ck;

ORACLE
- Insert possible with marks value as 500
- Update possible excluding marks column
- Delete possible
DROPPING VIEWS
SQL> drop view dept_v;
SYNONYM AND SEQUENCE
SYNONYM
A synonym is a database object, which is used as an alias for a table, view or sequence.
TYPES
 Private
 Public
Private synonym is available to the particular user who creates.
Public synonym is created by DBA which is available to all the users.
ADVANTAGES
 Hide the name and owner of the object.
 Provides location transparency for remote objects of a distributed database.
CREATE AND DROP
SQL> create synonym s1 for emp;
SQL> create public synonym s2 for emp;
SQL> drop synonym s1;
SEQUENCE
A sequence is a database object, which can generate unique, sequential integer values.
It can be used to automatically generate primary key or unique key values.
A sequence can be either in an ascending or descending order.

ORACLE
Syntax:
Create sequence <seq_name> [increment bty n] [start with n] [maxvalue n] [minvalue
n]
[cycle/nocycle] [cache/nocache];
By defalult the sequence starts with 1, increments by 1 with minvalue of 1 and with nocycle,
nocache.
Cache option pre-alloocates a set of sequence numbers and retains them in memory for
faster access.
Ex:
SQL> create sequence s;
SQL> create sequence s increment by 10 start with 100 minvalue 5 maxvalue 200 cycle
cache 20;
USING SEQUENCE
SQL> create table student(no number(2),name varchar(10));
SQL> insert into student values(s.nextval, ‘saketh’);
 Initially currval is not defined and nextval is starting value.
 After that nextval and currval are always equal.
CREATING ALPHA-NUMERIC SEQUENCE
SQL> create sequence s start with 111234;
SQL> Insert into student values (s.nextval || translate
(s.nextval,’1234567890’,’abcdefghij’));
ALTERING SEQUENCE
We can alter the sequence to perform the following.
 Set or eliminate minvalue or maxvalue.
 Change the increment value.
 Change the number of cached sequence numbers.
Ex:
SQL> alter sequence s minvalue 5;
SQL> alter sequence s increment by 2;

ORACLE
SQL> alter sequence s cache 10;
DROPPING SEQUENCE
SQL> drop sequence s;
JOINS
The purpose of a join is to combine the data across tables.
A join is actually performed by the where clause which combines the specified rows of
tables.
If a join involves in more than two tables then oracle joins first two tables based on the
joins condition and then compares the result with the next table and so on.
TYPES
Equi join
Non-equi join
Self join
Natural join
Cross join
Outer join
 Left outer
 Right outer
 Full outer
Inner join
Using clause
On clause
Assume that we have the following tables.
SQL> select * from dept;
DEPTNO DNAME LOC
------ ---------- ----------
10 mkt hyd
20 fin bang
30 hr bombay
SQL> select * from emp;

ORACLE
EMPNO ENAME JOB MGR DEPTNO
---------- ---------- ---------- ---------- ----------
111 saketh analyst 444 10
222 sudha clerk 333 20
333 jagan manager 111 10
444 madhu engineer 222 40
EQUI JOIN
A join which contains an ‘=’ operator in the joins condition.
Ex:
SQL> select empno,ename,job,dname,loc from emp e,dept d where e.deptno=d.deptno;
EMPNO ENAME JOB DNAME LOC
---------- ---------- ---------- ---------- ----------
111 saketh analyst mkt hyd
333 jagan manager mkt hyd
222 sudha clerk fin bang
USING CLAUSE
SQL> select empno,ename,job ,dname,loc from emp e join dept d using(deptno);
---------- ---------- ---------- ---------- ----------
ON CLAUSE
SQL> select empno,ename,job,dname,loc from emp e join dept d on(e.deptno=d.deptno);
---------- ---------- ---------- ---------- ----------

ORACLE
NON-EQUI JOIN
A join which contains an operator other than ‘=’ in the joins condition.
Ex:
SQL> select empno,ename,job,dname,loc from emp e,dept d where e.deptno > d.deptno;
---------- ---------- ---------- ---------- ----------
222 sudha clerk mkt hyd
444 madhu engineer mkt hyd
444 madhu engineer fin bang
444 madhu engineer hr bombay
SELF JOIN
Joining the table itself is called self join.
Ex:
SQL> select e1.empno,e2.ename,e1.job,e2.deptno from emp e1,emp e2 where
e1.empno=e2.mgr;
EMPNO ENAME JOB DEPTNO
---------- ---------- ---------- ----------
111 jagan analyst 10
222 madhu clerk 40
333 sudha manager 20
444 saketh engineer 10
NATURAL JOIN
Natural join compares all the common columns.
Ex:
SQL> select empno,ename,job,dname,loc from emp natural join dept;

ORACLE
---------- ---------- ---------- ---------- ----------
CROSS JOIN
This will gives the cross product.
Ex:
SQL> select empno,ename,job,dname,loc from emp cross join dept;
---------- ---------- ---------- ---------- ----------
222 sudha clerk mkt hyd
444 madhu engineer mkt hyd
111 saketh analyst fin bang
333 jagan manager fin bang
444 madhu engineer fin bang
111 saketh analyst hr bombay
222 sudha clerk hr bombay
333 jagan manager hr bombay
444 madhu engineer hr bombay
OUTER JOIN
Outer join gives the non-matching records along with matching records.
LEFT OUTER JOIN
This will display the all matching records and the records which are in left hand side table
those that are not in right hand side table.
Ex:

ORACLE
SQL> select empno,ename,job,dname,loc from emp e left outer join dept d
on(e.deptno=d.deptno);
Or
SQL> select empno,ename,job,dname,loc from emp e,dept d where
e.deptno=d.deptno(+);
---------- ---------- ---------- ---------- ----------
444 madhu engineer
RIGHT OUTER JOIN
This will display the all matching records and the records which are in right hand side table
those that are not in left hand side table.
Ex:
SQL> select empno,ename,job,dname,loc from emp e right outer join dept d
Or
SQL> select empno,ename,job,dname,loc from emp e,dept d where e.deptno(+) =
d.deptno;
---------- ---------- ---------- ---------- ----------
hr bombay
FULL OUTER JOIN
This will display the all matching records and the non-matching records from both tables.
Ex:
SQL> select empno,ename,job,dname,loc from emp e full outer join dept d

ORACLE
---------- ---------- ---------- ---------- ----------
444 madhu engineer
hr bombay
INNER JOIN
This will display all the records that have matched.
Ex:
SQL> select empno,ename,job,dname,loc from emp inner join dept using(deptno);
---------- ---------- ---------- ---------- ----------
SUBQUERIES AND EXISTS
SUBQUERIES
Nesting of queries, one within the other is termed as a subquery.
A statement containing a subquery is called a parent query.
Subqueries are used to retrieve data from tables that depend on the values in the table
itself.
TYPES
 Single row subqueries
 Multi row subqueries
 Multiple subqueries
 Correlated subqueries

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