On delete set null mysql

So in this example, if a product_id value is deleted from the products table, the corresponding records in the inventory table that use this product_id will have the product_id set to NULL. Verweise in der Detailtabelle auf NULL gesetzt. In addition to the ON DELETE clause, there is the ON UPDATE. SET NULL will set the foreign key to be NULL.

Content reproduced on this site is the property of the respective copyright holders. The foreign key cities. What if, however, cities. Foreign key constraints: When to use ON. Para una ON DELETE o ON UPDATE que no se especifica, la acción predeterminada es siempre RESTRICT.

RESTRICT: Rejects the delete or update operation for the parent table. Now obviously, this is going to require that the foreign key is not labelled NOT NULL. Antonio Rodrigo Guzmán.

Subscribe Subscribed. Hi, I did not get a real answer to my question two weeks ago, so I try it again: I try to create a table with two foreign key definitions like the following statement on a MaxDB 7. USERS ( ID integer not null , USERNAME varchar(100) not null , CREATED_BY integer, MODIFIED_BY integer, primary key (ID), FOREIGN KEY FK_USER_REFE. This is not a good idea in my opinion.

NO ACTION: Equivalente ao RESTRICT. ON DELETE CASCADE means that if the parent record is delete any child records are also deleted. Há ainda o SET DEFAULT: Define o valor da coluna na tabela filha, como o valor definido como default para ela, ao excluir ou atualizar um registro na tabela pai.

InnoDB i can write: on delete set null ! Am I misunderstanding something here? I have two tables, tableand table2. Tablealso has a TIMESTAMP field that has ON UPDATE CURRENT_TIMESTAMP set. Modifying an entry in tablesuccessfully updates the timestamp field.

Drop MySQL foreign key constraints. Uma exceção de violação de chave estrangeira é retornada. Riesenauswahl an Markenqualität. Folge Deiner Leidenschaft bei eBay! Die liebsten Fashion-Marken kaufen.

Von Generator bis Wäsche. Alles finden, was Sie brauchen. Wir machen die Rückgabe einfach. DELETE tFROM tLEFT JOIN tON t1. Bay hat alles für Sie!