Answer / allin

The Primarykey Constraint= unique + Not Null constraints.
For the Unique the meaning it self it is telling unique
value. won't accept duplicate values.

Thanks & Regards,
RatnaRao
9833847339

Answer / naren

When ever you create a primary key constraint on perticular
column in a table it creates clustered index by default,
it cannot allow null values and a table having only one
primary key constraint. But in the case of Unique Key
constraint, it allow only one null value, it creates non-
clustered index by default and a table having multiple
unique key constraints.


Regards
Naren Krishna

Answer / kiran

if unique then it can have null

but if column has primary then it cannot have null values
and duplicate values

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