Dotaz: mysql - CONSTRAINT - NO ACTION / RESTRICT

[Frant1]

Ahoj, mohl by mi nekdo rici jaky je rozdil mezi ON UPDATE NO ACTION / ON UPDATE RESTRICT nebo ON DELETE NO ACTION / ON DELETE RESTRICT pri vytvareni constrantu v mysql ? Nikde jsem nenasel, jestli je v pouziti NO ACTION a RESTRICT nejaky rozdil nebo ktere z nich by se melo v jakych pripadech pouzovat. Treba mi tu nekdo poradi.

Diky.

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Odpovědi

[mrazik]

Dokumentace rika:
RESTRICT: Rejects the delete or update operation for the parent table. Specifying RESTRICT (or NO ACTION) is the same as omitting the ON DELETE or ON UPDATE clause.

NO ACTION: A keyword from standard SQL. In MySQL, equivalent to RESTRICT. The MySQL Server rejects the delete or update operation for the parent table if there is a related foreign key value in the referenced table. Some database systems have deferred checks, and NO ACTION is a deferred check. In MySQL, foreign key constraints are checked immediately, so NO ACTION is the same as RESTRICT.
Tedy zaver je, ze je to stejne.

[Tarmaq]

tzn. je asi vhodne pouzivat spise tu standardni

NO ACTION

. IMHO ji teda ani nema cenu uvadet, vzdyt je to defaultni chovani.