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FOREIGN KEY (product_id) REFERENCES products (id) ON DELETE CASCADE. ON UPDATE CASCADE. )Engine=InnoDB; This way, you can delete a product OR a category, and only the associated records in categories_products will die alongside. The cascade won't travel farther up the tree and delete the parent product/category table.
12 sie 2021 · The first option is only valid for optional relationships where the foreign key property (and the database column to which it is mapped) must be nullable. The second option is valid for any kind of relationship and is known as "cascade delete".
If you want to change a foreign key without dropping it you can do: ALTER TABLE child_table_name WITH CHECK ADD FOREIGN KEY(child_column_name) REFERENCES parent_table_name (parent_column_name) ON DELETE CASCADE
3 lip 2019 · In this article, we will review on DELETE CASCADE AND UPDATE CASCADE rules in SQL Server foreign key with different examples. DELETE 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.
21 kwi 2011 · The foreign key relation can be created either through SSMS GUI or T-SQL. Rules for update/delete operations may be specified explicitly. However if nothing is specified then the default rule is No Action. The rule may be changed to any other option at any time later by recreating the FK relation.
1 sie 2012 · This tip will look at the DELETE CASCADE option when creating foreign key constraints and how it helps keep the referential integrity of your database intact.
19 mar 2024 · Two critical options that can be applied to foreign key constraints are ON DELETE CASCADE and ON UPDATE CASCADE. These options automate the maintenance of referential integrity between tables, but it's important to understand how they work and when they should be used.
