#entity constraint in sql server

Integrity constraints are pre-defined sets of guidelines used in Database Management Systems to apply to table fields (columns) or relations in order to maintain the general validity, integrity, and consistency of the data contained in the database table.

This post is intended to introduce integrity constraints, their need and their usage in SQL. Integrity constraints are pre-defined sets of guidelines used in Database Management Systems to apply to table fields (columns) or relations in order to maintain the general validity, integrity, and consistency of the data contained in the database table. The guidelines that the data columns in a table…