IBM Mainframe Forum

[ragur.satheesh]

Diff b/w primary key & Candidate key ?

[GuyC]

the definition of them

[ankesh.cs2007]

The primary key of a table is the column that uniquely identify the columns of that table. Primary key should be unique and not null.
Where as candidate key all those columns which are capable of being a primary key but not designated as primary key.

[dick scherrer]

Hello,

Where as candidate key all those columns which are capable of being a primary key but not designated as primary key.

Please post the link to the manual or other documentation that says this. . .

[ankesh.cs2007]

hay check out this link may this help
http://dotnetslackers.com/articles/sql/ ... y-Key.aspx

[dick scherrer]

Hello,

Please post the link to the manual or other documentation that says this. . .

The link posted is someone's personal article. Which is about an approach that i have never needed (but then, i've only been involved with the definition and implementation of a few hundred databases (not tables - thousands of them)).

Personally, i believe that proper design will almost always have the "primary key" jumping up and down making itself visable. Long ago this little "rule" was published about a primary key:
"every non-key attribute "must provide a fact about the key, the whole key, and nothing but the key - so help me Codd

fwiw