Question

what is mean by primary key

Answer 1

Heya!

If you're talking of MS access, then a primary is a matching field from one table used to relate a table to foreign keys in other tables. It creates a relationship between two tables.

A primary key does not allow null values and must always have a unique value.

An example - In a school database, the roll number of each student uniquely identities each student of a class. One might have the same name but roll differs. So in such databases, the roll field is the primary key.

Hope it helps!