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MySQL's Default ON DELETE Behavior: A Comprehensive Guide
In MySQL, the ON DELETE behavior defines the action to be taken on a child row when its related parent row is deleted. Understanding this behavior is crucial for maintaining database integrity.
The Five Options:
MySQL provides five possible ON DELETE behaviors:
Default Behavior:
The default ON DELETE behavior is NO ACTION, which means that MySQL will prevent any deletion or update that would break a foreign key constraint. If no ON DELETE clause is specified, the default behavior is assumed.
Other Options:
Understanding NO ACTION and RESTRICT:
NO ACTION and RESTRICT are essentially synonymous. Both options prevent foreign key violations by rejecting any operation that would break a constraint.
Conclusion:
The ON DELETE behavior is a critical aspect of database design, as it determines how child rows are affected when their parent rows are modified or deleted. By understanding the five available options and the default behavior, developers can ensure the integrity and consistency of their MySQL databases.
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