Tuesday, 19 June 2018

UNIQUE KEY

The UNIQUE constraint uniquely identifies each record in a database table. There can be many UNIQUE constraints per table. 

A Unique key column can contain NULL values.

Syntax :-

   CREATE TABLE student
   (
    Name varchar (30),
    Roll integer (5),
    Mobile_no integer (10) UNIQUE KEY
    );

Example :-

CREATE TABLE u_tab
(
stu_id int (5) UNIQUE KEY,
name varchar (30),
roll int (5) UNIQUE KEY,
city varchar (40)
);


Insert Table :-




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