How to Properly Delete Records from Multiple Tables in MySQL?

MySQL multi-table record deletion skills

Deleting records from multiple MySQL tables simultaneously is a complex task. Directly using a DELETE statement with a WHERE clause that contains multiple table references will usually fail. For example, the following code:

DELETE FROM `pets` p,
            `pets_activities` pa
      WHERE p.`order` > :order
        AND p.`pet_id` = :pet_id
        AND pa.`id` = p.`pet_id`

Usually produces errors like this:

Uncaught Database_Exception [1064]: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'p, pets_activities pa...'

The correct approach is to use the JOIN keyword. The modified code is as follows:

DELETE p, pa
      FROM pets p
      JOIN pets_activities pa ON pa.id = p.pet_id
     WHERE p.order > :order
       AND p.pet_id = :pet_id

If you only need to delete records in the pets_activities table, you can use the following code:

DELETE pa
      FROM pets_activities pa
      JOIN pets p ON pa.id = p.pet_id
 WHERE p.order > :order
   AND p.pet_id = :pet_id

These methods can effectively delete records from multiple tables in MySQL. Of course, there are other methods for single-table deletion involving referential integrity, such as EXISTS, NOT EXISTS, IN, and NOT IN. However, the above MySQL syntax provides a general solution for multi-table deletion, especially when dealing with complex deletion scenarios.

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