What is data integrity?

Data integrity is a database property that guarantees correctness, consistency, and reliability of information while it's being stored and processed.

#The main types of integrity

1. Entity Integrity

• Every record in a table must have a unique identifier (a primary key).
• This ensures there are no duplicate or "empty" records.

2. Referential Integrity

• A foreign key's values must match existing values of the primary key in the other table.
• It prevents "orphaned references", for example, an employee can't reference a department that doesn't exist.

3. Domain Integrity

• A field's values must match the allowed data type and constraints (e.g. number, text, date).
• For example, the Age field can't hold the text "thirty".

4. User-defined Integrity

• Additional rules set by business logic, for example: a salary can't be negative.

Put simply, data integrity guarantees that the database holds truthful, logical, consistent information, and that no data operation breaks these rules.