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