背景:
一张表 有 name , crt_time , work_sts 三个字段
这张表里存在这样的数据
'a', '2018-12-18 21:37:24', '未'
'a', '2018-12-19 09:37:24', '完'
'a', '2018-12-19 21:37:24', '未'
'b', '2018-11-18 21:37:24', '完'
'b', '2018-11-19 20:37:24', '完'
'b', '2018-11-20 09:37:24', '完'
'c', '2018-11-18 21:47:24', '完'
'c', '2018-11-19 20:57:24', '完'
'c', '2018-11-20 09:33:24', '未'
'd', '2018-12-18 21:17:24', '未'
'd', '2018-12-19 09:17:24', '完'
'd', '2018-12-19 21:17:24', '完'
现在需要根据 name 去重 要求如下:
1. 同一个name下 work_sts没有 未 的时候 取 完 数据里 crt_time 最大的那条数据
2. 同一个name下 work_sts有一个 未 取 未 这条数据
3. 同一个name下 work_sts有多个 未 取 未 数据里 crt_time 最大的那条数据
答案:
SELECT a.* FROM t_test a JOIN( SELECT col1,MAX(col2) col2 FROM t_test WHERE col3='未' GROUP BY col1 HAVING SUM(IF(col3='未',1,0)) > 0 )b WHERE a.col1 = b.col1 AND a.col2 = b.col2 UNION SELECT a.* FROM t_test a JOIN ( SELECT col1,MAX(col2) col2 FROM t_test GROUP BY col1 HAVING SUM(IF(col3='未',1,0)) = 0 )c WHERE a.col1 = c.col1 AND a.col2 = c.col2 ORDER BY col1
CREATE TABLE `t_test` ( `col1` varchar(32) DEFAULT NULL COMMENT 'col1', `col2` varchar(128) DEFAULT NULL COMMENT 'col2', `col3` varchar(64) DEFAULT NULL COMMENT 'col3', `id` varchar(30) DEFAULT NULL ) ENGINE=InnoDB DEFAULT CHARSET=utf8 INSERT INTO `t_test` (`col1`, `col2`, `col3`, `id`) VALUES ('a', '2018-12-18 21:37:24', '未', '100'); INSERT INTO `t_test` (`col1`, `col2`, `col3`, `id`) VALUES ('a', '2018-12-19 09:37:24', '归', '100'); INSERT INTO `t_test` (`col1`, `col2`, `col3`, `id`) VALUES ('a', '2018-12-19 21:37:24', '未', '100'); INSERT INTO `t_test` (`col1`, `col2`, `col3`, `id`) VALUES ('b', '2018-11-18 21:37:24', '归', '100'); INSERT INTO `t_test` (`col1`, `col2`, `col3`, `id`) VALUES ('b', '2018-11-19 20:37:24', '归', '100'); INSERT INTO `t_test` (`col1`, `col2`, `col3`, `id`) VALUES ('b', '2018-11-20 09:37:24', '归', '100'); INSERT INTO `t_test` (`col1`, `col2`, `col3`, `id`) VALUES ('c', '2018-11-18 21:47:24', '归', '100'); INSERT INTO `t_test` (`col1`, `col2`, `col3`, `id`) VALUES ('c', '2018-11-19 20:57:24', '归', '100'); INSERT INTO `t_test` (`col1`, `col2`, `col3`, `id`) VALUES ('c', '2018-11-20 09:33:24', '未', '100'); INSERT INTO `t_test` (`col1`, `col2`, `col3`, `id`) VALUES ('d', '2018-12-18 21:17:24', '未', '100'); INSERT INTO `t_test` (`col1`, `col2`, `col3`, `id`) VALUES ('d', '2018-12-19 09:17:24', '归', '100'); INSERT INTO `t_test` (`col1`, `col2`, `col3`, `id`) VALUES ('d', '2018-12-19 21:17:24', '归', '100');