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Can a Single MySQL Query Delete Data from Multiple Tables Simultaneously?
Can a Single MySQL Query Delete Data from Multiple Tables Simultaneously?
Dec 12, 2024 pm 07:31 PM
Deleting Multiple Tables in MySQL with a Single Query
Having multiple tables storing user-related information can pose challenges when trying to efficiently remove user data. The question arises: "Is it possible to delete data from multiple tables simultaneously with a single query in SQL?"
The Approach:
The provided code implements a straightforward approach:
DELETE FROM table1 WHERE user_id='$user_id'; DELETE FROM table2 WHERE user_id='$user_id'; DELETE FROM table3 WHERE user_id='$user_id'; DELETE FROM table4 WHERE user_id='$user_id';
This approach involves executing separate DELETE statements for each table, cascading the deletion process. However, it may not be the most efficient or flexible option.
A Pivotal Revelation:
Remarkably, MySQL offers a more advanced technique to achieve this task. According to the official documentation, it is indeed possible to delete rows from multiple tables in a single query. By utilizing the JOIN syntax, we can establish relationships between tables based on a common condition (in this case, the user_id field).
The Revised Code:
The manual provides an illustrative example:
DELETE t1, t2 FROM t1 INNER JOIN t2 INNER JOIN t3 WHERE t1.id=t2.id AND t2.id=t3.id;
In our scenario, we can adapt this approach as follows:
DELETE user_info.* FROM user_info INNER JOIN table1 ON user_info.user_id = table1.user_id INNER JOIN table2 ON user_info.user_id = table2.user_id INNER JOIN table3 ON user_info.user_id = table3.user_id INNER JOIN table4 ON user_info.user_id = table4.user_id WHERE user_info.user_id = '$user_id';
By using this technique, we delete rows from all four tables related to the user specified by the $user_id in a single query, effectively mimicking the previous approach but with improved efficiency.
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