面试-Sql专题-4-列转行

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网的案例
##数据准备

CREATE TABLE `T_SCORE2` (
  `ID` int(10) NOT NULL AUTO_INCREMENT,
  `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;


insert into T_SCORE2(NAME, CN_SCORE, MATH_SCORE, EN_SCORE) values
("张三", 34, 58, 58),
("李四", 45, 87, 45),
("王五", 76, 34, 89);


-- 普通
select * from T_SCORE2;

##数据效果

##需要效果

##sql

select NAME, '语文' as COURSE , CN_SCORE as SCORE from T_SCORE2
union 
select NAME, '数学' as  COURSE, MATH_SCORE as SCORE from T_SCORE2
union 
select NAME, '英语' as  COURSE, EN_SCORE as SCORE from T_SCORE2
order by NAME,COURSE;