关于mysql删除语句的子查询问题

今天要删除letterrelation表中无效的数据，于是找出无效的letterrelationId

select letterRelationId from letterrelation where letterRelationId not in(select distinct letterRelationId from letter);

然后在前面加上delete语句

delete from letter where letterRelationId in(select letterRelationId from letterrelation where letterRelationId not in(select distinct letterRelationId from letter));

呵呵。报错了



于是后来百度好久，找到一个网址解答：http://zhidao.baidu.com/question/1831460432659159420.html

于是我就写下了自己的sql语句：

create table table_test as select letterRelationId from letterrelation where letterRelationId not in(select distinct letterRelationId from letter);
delete from letterrelation where letterRelationId in (select letterRelationId from table_test);
drop table table_test;

最后发现完美解决了。但是原因我说一下：

1网上的解释是说mysql工具不强大，无法做到对某个表进行查询了然后又进行删除操作，但是oracle可以做到。这样

算的话就是mysql不强大了。

2同事说是建立视图了，视图我不太了解，暂且等我先去研究一下