Database develop. life cycle - Data Integrity and Constraints

Data integrity ensures that data stored in a database remains accurate, consistent, and reliable throughout its lifecycle. Maintaining integrity is essential because incorrect or inconsistent data can lead to wrong decisions and system failures.

Integrity is enforced using constraints, which are rules applied to database tables. Entity integrity ensures that each record is uniquely identifiable using a primary key. Referential integrity maintains valid relationships between tables using foreign keys. Domain integrity restricts data values using data types, ranges, and conditions.

Constraints such as NOT NULL, UNIQUE, CHECK, and DEFAULT prevent invalid data from entering the database. For example, a NOT NULL constraint ensures mandatory fields are not left empty.

By enforcing data integrity, databases maintain correctness, prevent duplication, and ensure long-term data reliability.