SQL IS CATEGORIED INTO 5 TYPES BASED ON OPERATION ON DATABASE
THEY ARE:
1).DDL[Data Definition Language]
example: create ,truncate ,alter, flashback, rename, drop
2).DML[Data Manipulation Language]
example: update ,delete ,insert, insert all, merge
3).DCL[Data Control Language]
example: grand , revoke
4).TCL[Transaction Control Language]
example: rollback, save point, commit
5).DQL[Data Query Language]
example: selects
LET’S DESCRIBE EVERYTHING IN DETAIL:
Data Types:
Char(size):
we use these char type for the fields which has the fixed size like state code .
example char(2);TG,AP pan card number[10 characters]
VARCHAR2(SIZE):
we use these when the data size is un predictable .the extra bytes are released.
LONG:
it can hold characters up to 2GB.no need to mention the size for these.
CLOBE:
it allows large objects characters up to 4 GB.
UNICODE:
includes characters belongs to different languages.
NUMERIC:
Number(p):
allows without decimal up to 38 digits.
Number(p ,s):
s→ SCALE: number of digits after decimal.
p→ PRECISION: number of digits allowed it can be up to 38 digits
DATE:
Allows date and time .
time is optional if time not mentioned it stores as the default 12:00 am
FORMAT:DD/MON/YYYY