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 values …
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 Orders table is a …
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 two tables …
SQL Foreign Key: Keep Your Database Relationships in Check
Dec 3, 2025 · A foreign key is a field or set of fields in one table that refers to the primary key in another table. This foreign key creates a link between tables to ensure that the data in the referencing table …
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 the …
Foreign Key Constraint in SQL: Building Relationships in Your Database
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 stays consistent …
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 that don’t …
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 data consistency.
Foreign Key in DBMS - GeeksforGeeks
Jan 6, 2026 · Foreign keys are a set of constraints in DBMS that establish relationships between tables and also ensure consistency and integrity of data. A foreign key is applied to a column (or attribute) …