Unique Key Problem

Question

Database : SQL SERVER 2005
Front-End : Visual Studio 2005
I create table T1 with columns : EMPNUM numeric(3,0),EMPName varchar(25)

EMPNUM is unique key.

I insert NULL value in EMPNUM.

It allows inserting of NULL value once only then it will give error about violating of Unique Key.

If you have solution let me know in brief as soon as possible.

Vijay Yadav · Answer

Hi Ashfaq If you have unique key then it will allows the null value only once so as to maintain uniqueness throughout the table because unique key does not allow the same value again.ok!!! Thanks Vijay

Suthish Nair · Answer

Ashfaq Please explain this line and give more details. It allows inserting of NULL value once only then it will give error about violating of Unique Key.

Santhosh N · Answer

unique does allow unique values..null being one unique value it allows once.. if u dont want to allow..go for primary key so that it does not allow