Question

what is primary key. why we need primary key.

Answer 1

Hey !$<b>$

It is a column (or columns) in a table that uniquely identifies each row. A primary key value is  unique and cannot be null. There is only one primary key for a table.

Answer 2

Explanation:

it differentiate the record in a file . we need it because it is required for every table to identify record uniquely