wahts is mean by primary key and unique key?
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Answer Posted / bhausaheb.chate
Primary Key:- Primary Key is an attribute or a set of
attributes in a table which uniquely identifies a record
(row) in a table and no two records (rows) in the table can
have the same values for all the columns comprising the
primary key.
Unique Key:- A unique key is a key which stores unique
values (no duplicates) for that particular column.
Difference between Primary Key & Unique Key:-
1. A Unique key can store a null value and primary key
cannot store any null value.
2. A primary key can be references to another table as a
Foreign Key.
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