Why should we set the primary key as not null

imain · New User Joined: 25 Jun 2006 Posts: 14 Location: US

HI All

Can anyone tell me the difference between setting the primary key and creating an index?
Why should we set the primary key as not null?
What difference is there in an index when the index is created as UNIQUE?

THanks in advance
imain

Jerry · New User Joined: 16 Sep 2005 Posts: 42

Hi imain,

I guess this link would help you, in case you had not gone through it before:

www.ibmmainframes.com/viewtopic.php?t=10227&highlight=primary+key[url][/url]