Data Integrity

Data Integrity validates the data before getting stored in the columns of the table.

SQL Server supports four type of data integrity:

Entity Integrity

Entity Integrity can be enforced through indexes, UNIQUE constraints and PRIMARY KEY constraints.

Domain Integrity

Domain integrity validates data for a column of the table.

It can be enforced using:

Foreign key constraints,

Check constraints,

Default definitions

NOT NULL.

Referential Integrity

FOREIGN KEY and CHECK constraints are used to enforce Referential Integrity.

User-Defined Integrity

It enables you to create business logic which is not possible to develop using system constraints. You can use stored procedure, trigger and functions to create user-defined integrity.