Add foreign key mysql xampp

The innodb storage engine supports foreign keys in Mysql.
To create foreign keys in phpmyadmin :

1. Convert both tables into innodb, if they are not already.

2. View the structure of the table which will have a foreign key. Make the referencing field an INDEX.

3. Now come back to structure view and click Relation view.

Phpmyadmin Relation View Link

In the Relation view page the field (which was made an INDEX) can be made a foreign key referencing to some other field in another table.

Phpmyadmin Foreign Key

That should do it.

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2018-06-17 2022-09-02  -  Web

In SQL database language in general, and in particular in PHPMyAdmin, a foreign key is a field of a table of the database that is depending on the field of another database.

PHPMyAdmin: foreign key, what is it?

In SQL database language in general, and in particular in PHPMyAdmin, a foreign key is a field of a table of the database that is depending on the field of another database.

This means that it is not possible to create an entry in a table referencing via a foreign key another table, if the other table does not contain an entry corresponding to the foreign key being inserted.

For example, this is like linking a bottle and its cork – you can’t use the cork if the bottle isn’t there.

By adding a PHPMyAdmin foreign key to a table, you will make sure that any entry in that table has a direct reference to a unique entry entry of another table. A generally accepted good practice is to create PHPMyAdmin foreign key to reference other tables indexed fields, such as primary keys, unique keys or indexed keys, in order to make sure that a single entry is uniquely referenced by the PHPMyAdmin foreign key created.

PHPMyAdmin foreign key and table relations - Relations — phpMyAdmin 5.1.0-dev documentation

Adding a foreign key in phpMyAdmin is pretty simple, but the option might be difficult to find.

Open the table in which you want to add the foreign key. Go to the tab Structure, in which you will find a sub menu called Relation View. There, select the column which will hold the foreign key, and the table and column referenced by this key.

As the menus might be pretty difficult to find, refer to below screenshots.

It is also possible to add a foreign key with following SQL code :

ALTER TABLE `table1` ADD FOREIGN KEY (`FK_table2`) REFERENCES `table2` (`ID`) ON DELETE RESTRICT ON UPDATE RESTRICT;

Create foreign key phpmyadmin

Creating a foreign key allow for several options, including making sure that a column only contains entries existing in another table, possibility to prevent deletion of entries in the other table, or to cascade the deletion to referenced tables.

But one of the most useful options, in the phpMyAdmin interface, is to get a dropdown list with entries of the other table, when inserting entries in a table containing foreign keys.

It is even possible to decide which value is displayed by default from a table, when this is one is referenced by a foreign key in another table, as per below example.

How to use foreign key in PHPMyAdmin

In the foreign keys constraints section of a table, an indexed column can be set as a foreign key, simply using the graphical user interface.

How to remove foreign key in PHPMyAdmin

Open the table in which you want to remove a foreign key in the PHPMyAdmin interface. Go to structure > relation view, and there, click on “DROP” button in the line corresponding to the foreign key you want to delete relationship in PHPMyAdmin.

PHPMyAdmin relation view missing

The relation view is located under the Structure tab name, after a table has been selected from the PHPMyAdmin graphical user interface.