mysql Error1093错误

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不支持，在一条语句对同一个表，先查询再更新的操作。

解决方法1：改成sql

比如：利用临时表 

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

解决方法2：

官方说：可以通过设置optimizer_switch的 derived_merge参数来解决。

备注：Oracle是不会这个问题的

本文出自 “corasql” 博客，请务必保留此出处http://corasql.blog.51cto.com/5908329/1912236

mysql Error1093错误

标签：mysql 1093