行轉列
數據準備
建表：
CREATE TABLE `student` (
`ID` int(10) NOT NULL AUTO_INCREMENT,
`USER_NAME` varchar(20) DEFAULT NULL,
`COURSE` varchar(20) DEFAULT NULL,
`SCORE` float DEFAULT '0',
PRIMARY KEY (`ID`)
) ENGINE=InnoDB AUTO_INCREMENT=10 DEFAULT CHARSET=utf8;
新增數據：
insert into student(USER_NAME, COURSE, SCORE) values
("張三", "數學", 34),
("張三", "語文", 58),
("張三", "英語", 58),
("李四", "數學", 45),
("李四", "語文", 87),
("李四", "英語", 45),
("王五", "數學", 76),
("王五", "語文", 34),
("王五", "英語", 89);
源數據：
行轉列圖一
SELECT user_name ,
MAX(CASE course WHEN '數學' THEN score ELSE 0 END ) 數學,
MAX(CASE course WHEN '語文' THEN score ELSE 0 END ) 語文,
MAX(CASE course WHEN '英語' THEN score ELSE 0 END ) 英語
FROM student
GROUP BY USER_NAME;
行轉列后：
行轉列圖二
列轉行
數據準備
建表：
CREATE TABLE `grade` (
`ID` int(10) NOT NULL AUTO_INCREMENT,
`USER_NAME` varchar(20) DEFAULT NULL,
`CN_SCORE` float DEFAULT NULL,
`MATH_SCORE` float DEFAULT NULL,
`EN_SCORE` float DEFAULT '0',
PRIMARY KEY (`ID`)
) ENGINE=InnoDB AUTO_INCREMENT=1 DEFAULT CHARSET=utf8;
新增數據：
insert into grade(USER_NAME, CN_SCORE, MATH_SCORE, EN_SCORE) values
("張三", 34, 58, 58),
("李四", 45, 87, 45),
("王五", 76, 34, 89);
源數據：
列轉行圖一.jpg
select user_name, '語文' COURSE , CN_SCORE as SCORE from grade
union select user_name, '數學' COURSE, MATH_SCORE as SCORE from grade
union select user_name, '英語' COURSE, EN_SCORE as SCORE from grade
order by user_name,COURSE;
列轉行后：
列轉行圖二.jpg
