Diff b/w primary key & Candidate key ?



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Diff b/w primary key & Candidate key ?

Postby ragur.satheesh » Mon Dec 13, 2010 12:16 pm

Diff b/w primary key & Candidate key ?
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Re: Diff b/w primary key & Candidate key ?

 

Re: Diff b/w primary key & Candidate key ?

Postby GuyC » Mon Dec 13, 2010 2:15 pm

the definition of them
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Re: Diff b/w primary key & Candidate key ?

Postby ankesh.cs2007 » Sun Jan 16, 2011 10:20 am

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.
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Re: Diff b/w primary key & Candidate key ?

Postby dick scherrer » Sun Jan 16, 2011 10:31 am

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. . .
Hope this helps,
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Re: Diff b/w primary key & Candidate key ?

Postby ankesh.cs2007 » Tue Jan 18, 2011 10:53 pm

hay check out this link may this help
http://dotnetslackers.com/articles/sql/ ... y-Key.aspx
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Re: Diff b/w primary key & Candidate key ?

Postby dick scherrer » Wed Jan 19, 2011 1:37 am

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
Hope this helps,
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