2. Oracle's Built-in Data Types
I.Q. 7. what is mean Data type in SQL ? And explain its different types.
A data type is a unit of data storage in a software
system.
Some of Oracle's built-in data types are:
Data Types
1. Number
2. Char
3. Varchar ( or ) Varchar2
4. Date
5. Time Stamp
6. Long
7. Raw
8. Long Raw
9. Lob ( Clob, Blob, Bfile & NCLob )
1)
Number Data Type :
It allows only numeric values
Maximum size is 38 digits
Syntax :
X Number ( P, (S));
P => It allow show many
digits to store
S => Size
Ex : X Number (5,2)
2)
Character Data type:
1. Char
2. Varchar
and Varchar2
3. Long
a)
Char:
It allows
alphanumeric characters ( Numbers + Characters )
Maximum size is
2000 Bytes/ Characters
Syntax : X
Char( S );
b) Varchar ( or )
Varchar2:
It allows
alphanumeric characters
Max size 4000
Bytes/ Characters
Memory allocation
is dynamic
Syntax :X Varchar2( S );
3)
Date:
It is used to
store date values
Max size is 7
Bytes
Syntax :X Date;
Timestamp:
It is used to
store date along with fraction of seconds.
Syntax :X Timestamp;
4)
Long:
It is used to
store information
Max size is 2 GB.
Only once we have
to use in entire table.
Syntax : X Long;
5)
Raw:
It is used to
store images
Max size is 2000
Bytes.
Syntax :X Raw;
6)
Longraw:
It is used to
store information as well as images.
Max size is 2GB
Syntax :X Longraw;
7)
Lob:
a)Clob :
It is used to
store huge information
Max size is 4 GB
Syntax :X Clob;
b)Blob :
It is used to
store images but in the form of binary format.
Max size is 4 GB
Syntax :X Blob;
c)Bfile :
It is used to
store the files.
Max size is 4 GB.
Syntax :X Bfile;
d)NCLob:
It is used to store
multiple languages ( Unicode Format )
I.Q. 8 What is difference between char, Varchar and
Varchar2 ?
Char
|
Varchar
|
Varchar2
|
Fixed length data type
Maximum size 2000 byte
String values will be space/blank
padded before stored on disk.
CHAR is faster than VARCHAR
If this type is used to store variable
length strings, it will waste a lot of disk space.
|
Variable length data type
Maximum size 2000 byte
VARCHAR is going to be replaced by VARCHAR2
in next version.
|
Variable length data type
Maximum size 4000 byte
|
I.Q. 9 What is Boolean Data type?
A BOOLEAN data type enables you to
represent logical values. In code, BOOLEAN values are represented by
values for "no" and "yes" (in any combination of uppercase
and lowercase characters). You can represent BOOLEAN values, using:
·
YES, TRUE, ON
·
NO, FALSE, OFF
