Can you explain what is meant by data integrity in a database?

Data integrity in a database is a set of rules and mechanisms that ensure the correctness, consistency, and reliability of data.

Main types of integrity:

• Entity integrity — guarantees that each record is unique (for example, through a primary key).
• Referential integrity — ensures the correctness of relationships between tables (for example, a foreign key must reference an existing record).
• Domain integrity — data in a column conforms to a specific type and range of values.

For example, if the "Orders" table has a foreign key to the "Customers" table, you cannot add an order with a non-existent customer — this maintains referential integrity.