In-depth study on MySQL's data deletion from multiple tables

We have talked a lot about how to delete multi-table data in MySQL. The following is an in-depth analysis and discussion on how to delete multi-table data in MySQL, I hope you will learn how to delete multi-table data in MySQL.

1. delete from t1 where Condition

2. delete t1 from t1 where Condition

3. delete t1 from t1, t2 where conditions

4. delete t1, t2 from t1, t2 where conditions

The first three are feasible, and 4th are not feasible.

That is to say, a simple delete statement cannot be used to delete data from multiple tables. However, you can create a cascading delete relationship between two tables, you can delete the data in another table at the same time.

1. Delete all matching records with id values in Table T2.

DELETE t1 FROM t1, t2 WHERE t1.id = t2.id or delete from t1 USING t1, t2 WHERE t1.id = t2.id

2. Find and delete no matching records in data table T2.

DELETE t1 FROM t1 left join T2 ON t1.id = t2.id WHERE t2.id is null or

Delete from t1, USING t1 left join T2 ON t1.id = t2.id WHERE t2.id IS NULL

3. Find the data with the same record from the two tables and delete the data from both tables.

DELETE t1, t2 from t1 left join t2 ON t1.id = t2.id WHERE t1.id = 25

Note that delete t1, t1 in t2 from, and t2 cannot be aliases.

For example, delete t1, t2 from table_name as t1 left join table2_name as t2 on t1.id = t2.id where table_name.id = 25 execution in data is incorrect MYSQL version not less than 5.0 is acceptable in 5.0)

The preceding statement is rewritten

Delete table_name, table2_name from table_name as t1 left join table2_name as t2 on t1.id = t2.id where table_name.id = 25 execution in the data is incorrect. MYSQL versions earlier than 5.0 are acceptable in MYSQL 5.0)

Combination of multiple MySQL table result sets

Implementation of MySQL table sharding

MySQL authorization table usage example

Implementation of MySQL multi-Table Deletion

Advantages and disadvantages of MySQL independent tablespace