Answer / rahul khanke

primary key : primary key dose not except null value
unique key : it accept null values.. if it set to not null
then it as good as primary key.

Answer / hema

Unique :: it does not allow duplicate values but allows
null values.
Primary:: Primary does not allow duplicate values as wel as
it dosnt allow null values.

unique+not null==Primary key...

Answer / dhanashree

Unique Key can be NULL
But
Primary Key can not be NULL

Answer / madhu

unique key:
1.unique key will accept more than one null value.
2.whenever u created a unique key, then internally one non-clustered index will be created(one table can have more than one Non-clustered index).
3.one table can have more than one unique key.
Primary key:
1.One table should have one primary key only.
2.primary key will not accept null values.
3.whenever u created a primary key then internally one clustered index will be created(one table can have only one clustered index).

Answer / gourvendra singh

Unique : One or more unique key in a table,
allow only one null in the field.

Primary :Only one primary key in a table and u cannot
insert null into it.

Answer / nagurthilak

Through Unique key we cant establish the relation between to
two tables but from primary key it is possible

Answer / l..l.n.reddy

PRIMARY KEY:- only one primary key in a table.

UNIQUE KEY:- One or more unique key in a table.

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