Shulou(Shulou.com)06/01 Report--

Scene demonstration: mysql> create table test (id int,name varchar(12),primary key(id));Query OK, 0 rows affected (0.04 sec)mysql> insert into test values(1,'ttt');Query OK, 1 row affected (0.00 sec)mysql> insert into test values(2,'ttt');Query OK, 1 row affected (0.00 sec)mysql> commit;Query OK, 0 rows affected (0.00 sec)mysql> update test set name='aaaa' where id in (select id from test);ERROR 1093 (HY000): You can't specify target table 'test' for update in FROM clause

Official note:

Error: 1093 SQLSTATE: HY000 (ER_UPDATE_TABLE_USED)

Message: You can't specify target table '%s' for update in FROM clause

This error occurs for attempts to select from and modify the same table within a single statement. If the select attempt occurs within a derived table, you can avoid this error by setting the derived_merge flag of the optimizer_switch system variable to force the subquery to be materialized into a temporary table, which effectively causes it to be a different table from the one modified. See Section 9.2.2.3, "Optimizing Derived Tables and View References".

MySQL does not support querying and updating the same table in a statement.

Solution 1: Change to SQL

For example, using temporary tables

mysql> update test set name='aaaa' where id in (select id from (select id from test)c);Query OK, 2 rows affected (0.02 sec)Rows matched: 2 Changed: 2 Warnings: 0

Solution 2:

This can be resolved by setting the derived_merge parameter of optimizer_switch.

Note: Oracle does not have this problem.

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