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26 wrz 2009 · ON UPDATE CASCADE: SQL Server updates the corresponding rows in the child table when the rows in the parent table are updated. ON UPDATE SET NULL : SQL Server sets the rows in the child table to NULL when the corresponding row in the parent table is updated.
ON UPDATE CASCADE: the best one usually: if you update a company_id in a row of table COMPANY the engine will update it accordingly on all USER rows referencing this COMPANY (but no triggers activated on USER table, warning). The engine will track the changes for you, it's good.
21 sie 2024 · In PostgreSQL, the ON UPDATE CASCADE clause in a foreign key constraint allows for a cascading update behavior between linked tables. This feature automatically updates all matching values in the referencing columns of child tables when a value is changed in the referenced column of the parent table.
22 sie 2014 · 1) ON DELETE CASCADE means if the parent record is deleted, then any referencing child records are also deleted. ON UPDATE defaults to RESTRICT, which means the UPDATE on the parent record will fail. 2) ON DELETE action defaults to RESTRICT, which means the DELETE on the parent record will fail.
CASCADE: Delete or update the row from the parent table and automatically delete or update the matching rows in the child table. Both ON DELETE CASCADE and ON UPDATE CASCADE are supported.
20 cze 2013 · There are five options for ON DELETE and ON UPDATE that can apply to the FOREIGN KEY. These are called <referential actions>, directly from the SQL:2011 spec. ON DELETE CASCADE: if a row of the referenced table is deleted, then all matching rows in the referencing table are deleted.
17 sie 2017 · The ON UPDATE CASCADE tells the database that when an update occurs on the referenced column from the parent table (“id”), it must automatically update the matching rows in the child table (“books”) with the new value.
