实现从图一转行成图二的功能:
图一:
图二:
建表语句:
CREATE TABLE `t_user_score` (
`id` int(11) NOT NULL AUTO_INCREMENT COMMENT '主键' ,
`cname` varchar(10) CHARACTER SET utf8 COLLATE utf8_general_ci NULL DEFAULT NULL ,
`cource` varchar(10) CHARACTER SET utf8 COLLATE utf8_general_ci NULL DEFAULT NULL ,
`score` int(11) NULL DEFAULT NULL ,
PRIMARY KEY (`id`)
)
ENGINE=InnoDB
DEFAULT CHARACTER SET=utf8 COLLATE=utf8_general_ci
;
插入测试数据:
INSERT INTO `coco_test`.`t_user_score` ( `cname`, `cource`, `score`) VALUES ( '小许', '语文', '');
INSERT INTO `coco_test`.`t_user_score` ( `cname`, `cource`, `score`) VALUES ( '小许', '数学', '');
INSERT INTO `coco_test`.`t_user_score` ( `cname`, `cource`, `score`) VALUES ( '小许', '英语', '');
INSERT INTO `coco_test`.`t_user_score` ( `cname`, `cource`, `score`) VALUES ( '小张', '语文', '');
INSERT INTO `coco_test`.`t_user_score` ( `cname`, `cource`, `score`) VALUES ( '小张', '数学', '');
INSERT INTO `coco_test`.`t_user_score` ( `cname`, `cource`, `score`) VALUES ( '小张', '英语', '');
实现sql:
-- 行转列
SELECT cname ,
MAX(CASE cource WHEN '数学' THEN score ELSE 0 END ) 数学,
MAX(CASE cource WHEN '语文' THEN score ELSE 0 END ) 语文,
MAX(CASE cource WHEN '英语' THEN score ELSE 0 END ) 英语
FROM t_user_score
GROUP BY cname;