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« Yii 1.1 Application Development Cookbook中文翻译（第二章）

 如何删除Mysql表中的重复记录呢？最容易想到的直接办法（假设我想删除字段orderNum中的重复项）：

delete from cbfinancials where id in

(select id from cbfinancials group by orderNum having count(1)>1);

但遗憾的是这样写Mysql会提示错误：You can't specify target table 'cbfinancials ' for update in FROM clause

我们可以这样来解决：

delete from cbfinancials where id in

(select tmp.id from (select * from cbfinancials) as tmp

group by orderNum having count(1)>1);

把两个表分开，第二个用临时表，避免select和delete为同一个表，这样就不会报错了。