REGARDING PRIMARY KEY AND UNIQUE KEY

ashwinreddy

Hai

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

maximum number of primary key's for a table.

ashwin

anuradha · Global Moderator Joined: 06 Jan 2004 Posts: 257

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: 18

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 · Active User Joined: 30 Jul 2004 Posts: 98

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 Post subject: hi ashwin

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