Question

what is primary key in a table

Answer 1

primary key is the key that uniquely identifies each record in a table.it does not allow any null values and helps to reduce duplication of data

Answer 2

Answer:

Primary key : Each table compulsory needs one primary key. It is a main key that can uniquely identified each record in a table.

Explanation:

student name    student roll   student age

1)  a paul                   01                     13

2) a paul                   12                     12

3) c shukla                21                    13

4) d das                    78                     13

here, the primary key is student roll. This the main key which identify each record uniquely. Student name and student age can repeat more than one time. But Student roll number can not repeat any number of times. Always it it holds unique value. Here, Student roll column indicates primary key.