SQL FOREIGN KEY - W3Schools
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.
SQL Foreign Key Constraint - GeeksforGeeks
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 …
Create Foreign Key Relationships - SQL Server | Microsoft Learn
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 Essential Guide To SQL Foreign Key Constraint
This tutorial helps you understand SQL foreign key and show you how to define a foreign key using the FOREIGN KEY constraints.
SQL FOREIGN KEY Constraint (With Examples) - Programiz
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 …
Understanding Foreign Keys - SQL Tutorial
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 …
What Is a Foreign Key Constraint in SQL? - dbschema.com
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 …
Foreign Key in SQL: Definition and Examples - Intellipaat
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 …
Foreign Key Constraint in SQL: Building Relationships in Your …
May 25, 2025 · The foreign key constraint is your key to building reliable relationships in SQL databases. By linking tables and enforcing referential integrity, foreign keys ensure your data …
SQL Foreign Key: Keep Your Database Relationships in Check
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.