select * from a as a where a.id in (1,2,3,...,100)效率如何

[ypfei3345]

select * from a as a where a.id in (1,2,3,...,100)效率如何
in里面的东西是没有规律的
是从另一个表按条件select出来的

是单这么写效率好,还是select * from a as a inner join b as b on b.xx=xx and a.xx=b.xx效率好

[ypfei3345]

select * from a as a where a.id in (1,2,3,...,100)

select * from a as a where a.id=1;
select * from a as a where a.id=2;
.....
select * from a as a where a.id=99;
select * from a as a where a.id=100;

上面肯定比下面的效率好,对吧

[rucypli]

少了好多解析的时间

[ACMAIN_CHM]

[Quote]上面肯定比下面的效率好,对吧[/Quote]不一定。

http://topic.csdn.net/u/20090626/16/65f043cf-b9d9-4707-b660-9857461177f4.html
[求证&散分]MySQL 中 where id in (1,2,3,4,...) 的效率问题讨论

[ypfei3345]

恩,貌似没有人来个一锤定音的答案
看了那个帖子,感觉是数据量很小||数据量很大的时候,in的效率会好
但是不知道这个度是多少

小于10条能否认为in的效率好

[ACMAIN_CHM]

[Quote]是从另一个表按条件select出来的[/Quote]如果这样，为什么不直接用JOIN查询？

[加油馒头]

那还是用join吧