What is foreign key nedir?

Foreign key is a database constraint that links two tables together by using a shared column between them. The foreign key column is referred to as the "child" or "dependent" column while the matching column in the referenced table is referred to as the "parent" or "master" column. The purpose of using foreign keys is to enforce referential integrity between tables and to ensure data consistency. When a foreign key is defined, it ensures that any data inserted or updated in the child table must match the values in the parent table, preventing inconsistencies or errors that can occur if the data is not properly linked between tables. Additionally, foreign keys can be used to cascade updates or deletes from the parent table to the child table, making it easier to maintain data integrity throughout the system.