REGARDING PRIMARY KEY AND UNIQUE KEY

ashwinreddy · Posted: Tue Oct 05, 2004 1:17 pm

Hai

i want difference b/w primary key and unique key.

maximum number of primary key's for a table.

ashwin

anuradha · Posted: Tue Oct 05, 2004 1:32 pm

Hi Ashwin,

Unique key in the sense it will not have any value repeated to that particular key but primary key(also unique) makes the total row unique.

Thanks,
Anu

unna · New User Joined: 15 Oct 2004 Posts: 17

Hi,
I Suppose Primary key and unique key both mean the same .
Primary key is used for unique identification of a row and should not
have null values. There can be only one primary key for a table.

Thanks,

veerababu · New User Joined: 07 Nov 2004 Posts: 3

The main Difference is that

Primary key means ----- No Duplicates and No Nulls.

Unique key means ------ No Duplicates but Allows Nulls.

veerababu · New User Joined: 07 Nov 2004 Posts: 3

Hi,

ksivapradeep · New User Joined: 30 Jul 2004 Posts: 95

hello veera babu,

i think another diff b/w pkey and ukey is we can create more than one primary for a table and we cant create more than one ukey for a table is it correct r not.

regards,
siva pradeep

i413678 · Posted: Sat Feb 19, 2005 2:44 pm

the difference between unique and primary key is

primary key : notnull and unique

unique key is : avoids duplicates only.

more over one table can have only one primary key but more than one unique indexes.

any thing wrong or missed let me know.

Regards,
Pavan