What is the limit of the foreign key constraint in a database?

The scope of a foreign key constraint in a database is the specific table where it is defined. A foreign key links a column (or set of columns) in one table to the primary key or a unique key in another table, ensuring data integrity.

This constraint only applies within the database and the tables involved in the relationship. It guarantees that the values in the foreign key exist in the related table, preventing referential integrity violations.

For example, if the Orders table has a foreign key to the Customers table, the constraint applies to the values in Orders, checking their existence in Customers. It does not extend beyond the database or to other tables without explicit relationships.