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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.
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.
This tutorial introduces you to MySQL foreign key constraints and shows you how to manage foreign keys effectively.
How to declare a table with a foreign key in MySQL. To create a table with a FOREIGN KEY constraint, you denote the foreign key and the primary key that it references. The following code creates a table containing a foreign key:
22 kwi 2024 · A foreign key is a column or set of columns in a database table that is used to establish and focus a "referencing" relationship with the column or columns of another table. In essence, the foreign key is the bridge that connects two tables and is essential for maintaining data consistency.
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.
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.
