Referential Integrity

Difference Between Primary Key and Foreign Key

A primary key uniquely identifies each row in a table and cannot be NULL, while a foreign key is a column that references the primary key of another table to l…

What is Referential Integrity?

Referential integrity is a database rule ensuring that a foreign key value in one table always matches an existing primary key value in the referenced table, p…

ENUM Type vs Lookup Table: Which Should You Use?

An ENUM type is best for a small, genuinely fixed set of values that almost never changes and needs compact, fast storage, while a lookup table (a separate ref…

What Do ON DELETE CASCADE, SET NULL, and RESTRICT Mean for Foreign Keys?

These are referential actions attached to a foreign key that tell the database what to do to child rows when the referenced parent row is deleted or updated: C…

Soft Delete vs Hard Delete: What Is the Difference and When Do You Use Each?

A hard delete physically removes a row from the database with a DELETE statement, while a soft delete keeps the row in place but flags it as inactive using a c…