这个SQL有没优化的余地呢
select distinct(t.tid) from mcuhome_post t where t.uid = ‘1’ and isthread = 0
CREATE TABLE `mcuhome_post` (
`pid` int(10) unsigned NOT NULL AUTO_INCREMENT,
`tagid` mediumint(8) unsigned NOT NULL DEFAULT ‘0’,
`tid` mediumint(8) unsigned NOT NULL DEFAULT ‘0’,
`uid` mediumint(8) unsigned NOT NULL DEFAULT ‘0’,
`username` varchar(15) NOT NULL DEFAULT ”,
`ip` varchar(20) NOT NULL DEFAULT ”,
`dateline` int(10) unsigned NOT NULL DEFAULT ‘0’,
`message` text NOT NULL,
`pic` varchar(255) NOT NULL DEFAULT ”,
`isthread` tinyint(1) NOT NULL DEFAULT ‘0’,
`hotuser` text NOT NULL,
PRIMARY KEY (`pid`),
KEY `tid` (`tid`,`dateline`)
) ENGINE=MyISAM AUTO_INCREMENT=1 DEFAULT CHARSET=utf8;
tid是帖子的ID
我们这个post表是帖子的评论表，uid是参与评论的会员的id ,我们要检索出某个会员，参与过评论的帖子的所有tid 当然，同一篇帖子可以被同一个uid评论N次。现在要检索出某个uid的会员，所有评论过的帖子tid的集合。
试试
alter table mcuhome_post add index idx_th(uid,isthread,tid)
create index xx on mcuhome_post(uid,isthread,tid)
