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MySQL 相关项目
› MariaDB
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参考文档
› http://mysql-python.sourceforge.net/MySQLdb.html
关于 update table_1 set ... where table_1.id = (select table_1.id from table_1 where ...) 的问题
timepast · idyllim · May 29, 2014 · 5388 viewsThis topic created in 4355 days ago, the information mentioned may be changed or developed.
如题的语句在mysql中报错：You can't specify target table table_1 for update in FROM clause
解决办法是：
UPDATE table_1 SET set...
WHERE
table_1.x = (
SELECT pick.id FROM (SELECT tmp.id FROM table_1 tmp WHERE tmp.x = ? AND tmp.x = ?) pick )
但是这个语句的性能是不是不如分步操作的性能呢？
解决办法是：
UPDATE table_1 SET set...
WHERE
table_1.x = (
SELECT pick.id FROM (SELECT tmp.id FROM table_1 tmp WHERE tmp.x = ? AND tmp.x = ?) pick )
但是这个语句的性能是不是不如分步操作的性能呢？
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1
Dwyanetalk May 29, 2014
不明白这是要干什么？感觉在绕圈子……select后面的where直接当update的where不行吗？
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2
timepast OP @Dwyanetalk 报错
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3
lu18887 May 29, 2014
结合查询计划进行分析吧
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