Please refer to the below T-SQL script which creates a parent, child table and a foreign key on the child table with DELETE CASCADE rule. In this SQL, while creating a foreign key we have specified ON DELETE clause which tells, what needs to do when a record from the parent table is deleted.
PHPMYADMIN FOREIGN KEY DELETE CASCADE UPDATE
Similarly, we can create a foreign key with UPDATE CASCADE rule by selecting CASCADE as an action for the update rule in INSERT and UPDATE specifications. Step-1: Creating a database : Creating a database student by using the following SQL query as follows.
Once you click on Yes, a foreign key with delete rule is created. Steps for deleting rows when there is a foreign key in MySQL : Here, we will discuss the required steps to implement deleting rows when there is a foreign key in MySQL with the help of examples for better understanding. Docs User Guide Relations Edit on GitHub Relations phpMyAdmin allows relationships (similar to foreign keys) using MySQL-native (InnoDB) methods when available and falling back on special phpMyAdmin-only features when needed. In the INSERT and UPDATE specifications, select Cascade for the delete rule.Ĭlick on Close and save the table in the designer. select the foreign key column in the child table. Select the parent table and the primary key column in the parent table. Right click on the Keys folder and select New Foreign Key.Įdit table and columns specification by clicking … as shown in the below image. Login to the SQL Server using SQL Server Management Studio, Navigate to the Keys folder in the child table. Using the SQL Server Management Studio GUI:
PHPMYADMIN FOREIGN KEY DELETE CASCADE HOW TO
Let us see how to create a foreign key with DELETE and UPDATE CASCADE rules along with few examples.Ĭreating a foreign key with DELETE and UPDATE CASCADE rules Triggers on a table with DELETE or UPDATE cascading foreign key.Creating DELETE CASCADE and UPDATE CASCADE rule in a foreign key using T-SQL script.Creating DELETE and UPDATE CASCADE rule in a foreign key using SQL Server management studio.It won't touch any records where 'categoryid blue', and it would not travel onwards to the 'products' table, because there's no foreign key defined in that table. We will be discussing the following topics in this article: If you delete the 'red' category, the only records that will cascade delete in categoriesproducts are those where categoryid red. ) REFERENCES tblname (indexcolname. Defining a foreign key constraint cacade : when a row in the parent table is deleted or updated, the corresponding row in the child table is automatically. UPDATE CASCADE: When we create a foreign key using UPDATE CASCADE the referencing rows are updated in the child table when the referenced row is updated in the parent table which has a primary key. The definition must follow this syntax: CONSTRAINT symbol FOREIGN KEY indexname (indexcolname. In this article, we will review on DELETE CASCADE AND UPDATE CASCADE rules in SQL Server foreign key with different examples.ĭELETE CASCADE: When we create a foreign key using this option, it deletes the referencing rows in the child table when the referenced row is deleted in the parent table which has a primary key.
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