create temporary table tbd(id int) select id from d where para <> 1234;delete from t1 where id in (select id from tbd);
delete from t2 where id in (select id from tbd);
delete from t3 where id in (select id from tbd);
delete from t4 where id in (select id from tbd);drop table tbd;
新手求教,有无改进空间?怎么改进?
delete t1 from t2,d where t2.id=d.id;
delete t1 from t3,d where t3.id=d.id;
delete t1 from t4,d where t4.id=d.id;
delete t1 from t2,d where t2.id=d.id;
delete t1 from t3,d where t3.id=d.id;
delete t1 from t4,d where t4.id=d.id;
这样直接删除,比先select出来再删除快吗?我的想法是先select出来那么就不用做4遍查询了。