What is the purpose of referential integrity in database normalization?

The purpose of referential integrity in database normalization is to ensure the consistency and accuracy of data by establishing and enforcing relationships between tables. Referential integrity ensures that relationships between tables are maintained and that any changes made to the data are properly reflected in all related tables.

Referential integrity is achieved through the use of foreign keys, which are attributes in a table that refer to the primary key of another table. By defining these relationships, referential integrity ensures that data in the referencing table (foreign key table) corresponds to the data in the referenced table (primary key table).

The main objectives of referential integrity are:

1. Data Consistency: Referential integrity ensures that data remains consistent across tables. It prevents the creation of orphaned records, where a foreign key value in one table does not have a corresponding primary key value in the referenced table. This helps maintain the integrity and accuracy of the data.

2. Data Integrity: Referential integrity helps maintain the integrity of the database by preventing actions that could lead to data corruption or inconsistencies. It enforces rules such as cascading updates and deletes, which automatically propagate changes made to the primary key table to all related foreign key tables.

3. Data Validity: Referential integrity ensures that only valid data is stored in the database. It prevents the insertion of invalid foreign key values that do not exist in the referenced table. This helps maintain data quality and prevents data anomalies.

4. Data Reliability: Referential integrity enhances the reliability of the database by ensuring that data relationships are properly defined and maintained. It helps avoid data redundancy and duplication, as well as inconsistencies that can arise from incorrect or incomplete relationships.

In summary, referential integrity plays a crucial role in database normalization by enforcing relationships between tables, maintaining data consistency, integrity, validity, and reliability. It helps ensure that the database remains accurate, reliable, and efficient in handling data operations.