SQL新手求教这段有无优化空间？

[chenchenyangll]

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？

[码无边]

[Quote=引用 3 楼 的回复:]

引用 1 楼 的回复:

delete t1 from t1,d where t1.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？……
[/Quote]的却是要快一点的。

[ACMAIN_CHM]

delete t1 from t1,d where t1.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;

[bonlog]

你的目的是？

delete t1 from t1,d where t1.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;

[chenchenyangll]

[Quote=引用 1 楼 的回复:]

delete t1 from t1,d where t1.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;
[/Quote]

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。

[Rotel-刘志东]

explain ...不就知道了吗