The FOREIGN KEY constraint is a key used to link two tables together. A FOREIGN KEY is a field (or collection of fields) in one table that refers to the PRIMARY KEY in another table.

Dec 9, 2025 · A FOREIGN KEY constraint is a concept in SQL that enforces a valid relationship between two tables by ensuring that the values stored in the child table correspond to existing …

This tutorial helps you understand SQL foreign key and show you how to define a foreign key using the FOREIGN KEY constraints.

Nov 18, 2025 · This article describes how to create foreign key relationships in SQL Server by using SQL Server Management Studio or Transact-SQL. You create a relationship between …

The FOREIGN KEY constraint in SQL establishes a relationship between two tables by linking columns in one table to those in another. For example, Here, the customer_id field in the …

A foreign key is a field (or collection of fields) in one table that uniquely identifies a row of another table. The table containing the foreign key is known as the child table, and the table containing …

Jul 31, 2025 · A foreign key is a validation rule in the database that links one table to another by matching values. It helps keep your data linked correctly and stops you from adding values …

What Is a FOREIGN KEY in SQL? A FOREIGN KEY is a column (or a set of columns) in one table that establishes a link to the PRIMARY KEY of another table. This constraint ensures …

Dec 3, 2025 · A SQL foreign key links one table to another and prevents invalid data. It ensures you can’t reference records that don’t exist and keeps your data consistent.

Oct 29, 2025 · A foreign key in SQL is a column (or a set of columns) that links one table to the primary key of another table. It creates a relationship between two tables and helps maintain …