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Summary: in this tutorial, you will learn about the MySQL Foreign Key constraint and how to create, drop and disable a foreign key constraint. MySQL Foreign Key Introduction. A foreign key is a column (or set of columns) that establishes a relationship between data in two tables.
This tutorial introduces you to MySQL foreign key constraints and shows you how to manage foreign keys effectively.
The FOREIGN KEY constraint is used to prevent actions that would destroy links between tables. A FOREIGN KEY is a field (or collection of fields) in one table, that refers to the PRIMARY KEY in another table.
In MySQL, a Foreign Key is a column (or combination of columns) in a table whose values match the values of a Primary Key column in another table. Thus, using the Foreign key, we can link two tables together.
MySQL supports foreign keys, which permit cross-referencing related data across tables, and foreign key constraints, which help keep the related data consistent. A foreign key relationship involves a parent table that holds the initial column values, and a child table with column values that reference the parent column values.
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.
In this article, we introduced what foreign keys are, the rules for foreign keys, and how to use them in MySQL. In relational databases, foreign keys are used to define a constrained relationship between two entities. Foreign keys are useful for ensuring data integrity.
