candidate key

[Piya27]

Hi All,

How to add a candidate key in a table in SQl??

Please Help.

Thanks.

[babbu]

m not really sure but i think candidate key is the column which qualifies to be a primary key.
so u can set this column as primary key if u wish to at a later date.
but i dont think you can assign a candidate key

[__avd]

Priya,
Read this : http://databases.about.com/cs/specificproducts/g/candidate.htm

[Piya27]

What I actually want is to make one key of my table as candidate key.
I used keyword UNIQUE also but I was not able to accomplish the task.
Pls suggest.

[__avd]

set Primary key.

[Piya27]

set Primary key.

But Sir, I don't want to set the key as primary key..

Actually, I am sorry not to tell my problem in detail..

Specifically, I have a table with enrolno as primary key and I want to make classid As Candidate key, because I want to reference ClassID from a foreign key of another table. For that when I use the query to set FOREIGN KEY constraint that refers to the classid of this table,i get the error asking for classid to be either primary or candidate key..