How to query and delete a MySQL join table

MySQL join Table query and join table deletion are all frequently used operations. The following sections describe MySQL join Table query and table deletion in detail and hope to help you.

MySQL join Table query:

Reference mysql manul:
3.2.7. SELECT syntax 13.2.7.1. JOIN syntax
13.2.7.2. UNION syntax
Eg1: · mysql> SELECT t1.name, t2.salary FROM employee AS t1, info AS t2 ·-> WHERE t1.name = t2.name; eg2: · mysql> SELECT table1. * FROM table1 ·-> left join table2 ON table1.id = table2.id ·-> WHERE table2.id is null;

Join table deletion:

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)

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