Difference between primary key and unique key ?
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Answer Posted / yjreddy
primary key doesnt allow duplicates and null values
unique key allows null value only once
and more over
when you applying primary key by default clustered index is created on that table
when u applying unique key non clustered index is created on that table.
so primary key can be allowed only once(1) and unique u can apply more
than one on a single table(249)
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