将字段值作为字段显示

CREATE TABLE IF NOT EXISTS `user` (

  `userid` int(10) NOT NULL AUTO_INCREMENT,

  `username` varchar(30) NOT NULL,

  `password` varchar(32) NOT NULL,

  PRIMARY KEY (`userid`)

) ENGINE=MyISAM  DEFAULT CHARSET=utf8 AUTO_INCREMENT=5 ;



--

-- 转存表中的数据 `user`

--



INSERT INTO `user` (`userid`, `username`, `password`) VALUES

(1, 'zhangsan', 'd10906c3dac1172d4f60bd41f224ae75'),

(2, 'lisi', 'd10906c3dac1172d4f60bd41f224ae75'),

(3, 'wangwu', 'd10906c3dac1172d4f60bd41f224ae75'),

(4, 'zhaoliu', 'd10906c3dac1172d4f60bd41f224ae75');

　　

CREATE TABLE IF NOT EXISTS `pay` (

  `payid` int(10) NOT NULL AUTO_INCREMENT,

  `userid` int(10) NOT NULL,

  `payment` int(10) NOT NULL,

  `paytime` date NOT NULL,

  PRIMARY KEY (`payid`)

) ENGINE=MyISAM  DEFAULT CHARSET=latin1 AUTO_INCREMENT=7 ;



--

-- 转存表中的数据 `pay`

--



INSERT INTO `pay` (`payid`, `userid`, `payment`, `paytime`) VALUES

(1, 1, 100, '2001-10-12'),

(2, 1, 105, '2001-11-10'),

(3, 2, 50, '2001-11-28'),

(4, 3, 20, '2001-11-28'),

(5, 1, 10, '2012-11-28'),

(6, 3, 50, '2012-11-28');

　将字段值作为字段显示。　

select t1.userid,

sum(case `paytime` when '2001' then payment end) as '2001',

sum(case `paytime` when '2012' then payment end) as '2012'from

( select u.userid,year(p.paytime) paytime ,sum(p.payment) payment from `user` u inner join `pay` p on u.userid = p.userid 

group by u.userid,year(p.paytime)) t1 group by t1.userid

还有一个类似的结构：

select memberid,sum(member>10) as gt,sum(number<10) as lt from `order` group by `memberid`;

只是换了sum中的条件,用于统计行数。