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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
In this tutorial, you have learned how to use the MySQL ON DELETE CASCADE referential action for a foreign key to delete data automatically from the child tables when you delete data from the parent table.
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.
21 kwi 2011 · Foreign key constraints ensure the relational integrity of data in associated tables. A foreign key value may be NULL and indicates a particular record has no parent record. But if a value exists, then it is bound to have an associated value in a parent table.
Using the DELETE CASCADE option in your foreign key constraint definitions means better performance and less code when removing records from tables that have a parent-child relationship defined.
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.
