Difference Between primary key and unique key

Hi,
Can somebody explain me the difference between primary key
and unique key and in which scenarios we use them. please
explain with a example.
Regards
ChipThe primary distinction is that Primary key column(s) must be non-nullable
while Unique constraints allow a NULL value. Also, there can be only one
primary key in a table while there can be more than one Unique constraints
defined for a table.
Anith|||Hi,
Primary key :
- The key which will not allow any NULL Values.
- Will Create a Clustered Index by default.
Unique Key
- The Key will allow 1 Null Value
- Will Create a non clustered index by default
Since Primary key will not allow NULLS values it can be used in scenario to
preserve more data integrity
Thanks
Hari
MCDBA
"Chip" <anonymous@.discussions.microsoft.com> wrote in message
news:12c4c01c3f6a9$9ac762d0$a401280a@.phx
.gbl...
> Hi,
> Can somebody explain me the difference between primary key
> and unique key and in which scenarios we use them. please
> explain with a example.
> Regards
> Chip