MySQL in查询优化

开发说他写了个SQL特别慢，让看看。 html select * from t_channel where id_ in(select distinct cdbh from sjkk_gcjl where jgsj>'2015-01-02 08:00:00' and jgsj<'2015-01-02 12:00:00'); ...... 30min+ 而后我查询内部SQL,只须要3s+mysql

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