php - 使用 select 时子查询在 mysql 中返回多于 1 行

Question

我有两个表，用户和主题。

表用户

CREATE TABLE IF NOT EXISTS `user` (
  `userid` int(11) NOT NULL AUTO_INCREMENT,
  `usertype` int(11) DEFAULT '0',
  `useraccesskey` varchar(80) DEFAULT NULL,
  `userphone` varchar(80) DEFAULT NULL,
  `userpassword` varchar(80) DEFAULT NULL,
  `usernickname` varchar(80) DEFAULT NULL,
  `userphoto` varchar(80) NOT NULL,
  PRIMARY KEY (`userid`)
 ) ENGINE=InnoDB  DEFAULT CHARSET=utf8 AUTO_INCREMENT=1 ;

表格主题

CREATE TABLE IF NOT EXISTS `topic` (
 `topicid` int(11) NOT NULL AUTO_INCREMENT,
 `btid` int(11) NOT NULL,
 `topictitle` varchar(80) NOT NULL,
 `topiccontent` text NOT NULL,
 `topicisdel` int(11) NOT NULL,
 `topicdate` varchar(80) NOT NULL,
 `authorid` int(11) NOT NULL,
 `useraccesskey` varchar(80) NOT NULL DEFAULT '0',
 `topicistop` int(11) NOT NULL DEFAULT '0',
 `topicishot` int(11) NOT NULL DEFAULT '0',
  PRIMARY KEY (`topicid`)
) ENGINE=InnoDB  DEFAULT CHARSET=utf8 AUTO_INCREMENT=1605 ;

我使用这个 sql 查询来列出所有信息

select b.*, (select userphoto from user u where u.useraccesskey = b.useraccesskey) as headpic, (select usernickname from user u where u.useraccesskey = b.useraccesskey) as nickname from topic b where b.topicisdel = 0 and b.btid = 3 order by b.topicistop desc, b.topicishot desc, b.topicid desc"

但结果告诉我子查询返回超过1行，但我检查了所有信息，没有，我不知道为什么，请帮助我，谢谢。

Answer 1

所以看起来你正在追求类似这样的东西 - 尽管没有数据集和结果集，但总是愚蠢地很难确定......

select b.*
     , u.userphoto headpic
     , u.usernickname nickname
  from topic b
  join user u
    on u.useraccesskey = b.useraccesskey 
 where b.topicisdel = 0 
   and b.btid = 3 
 order 
    by b.topicistop desc
     , b.topicishot desc
     , b.topicid desc