MySQL行转列与列转行

行转列

例如：把图1转换成图2结果展示

图1 

 

图2

 

CREATE  TABLE  `TEST_TB_GRADE` (
  `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=1  DEFAULT  CHARSET=utf8;

 

insert  into  TEST_TB_GRADE(USER_NAME, COURSE, SCORE)   values
( "张三" ,  "数学" , 34),
( "张三" ,  "语文" , 58),
( "张三" ,  "英语" , 58),
( "李四" ,  "数学" , 45),
( "李四" ,  "语文" , 87),
( "李四" ,  "英语" , 45),
( "王五" ,  "数学" , 76),
( "王五" ,  "语文" , 34),
( "王五" ,  "英语" , 89);

　　

行转列SQL：

SELECT  user_name ,
    MAX ( CASE  course  WHEN  '数学'  THEN  score  ELSE  0  END  ) 数学,
    MAX ( CASE  course  WHEN  '语文'  THEN  score  ELSE  0  END  ) 语文,
    MAX ( CASE  course  WHEN  '英语'  THEN  score  ELSE  0  END  ) 英语
FROM  test_tb_grade
GROUP  BY  USER_NAME;

　　

列转行

例如：把图1转换成图3结果展示

图3

 

列转行SQL：

select  user_name,  '语文'  COURSE , CN_SCORE  as  SCORE  from  test_tb_grade2
union  select  user_name,  '数学'  COURSE, MATH_SCORE  as  SCORE  from  test_tb_grade2
union  select  user_name,  '英语'  COURSE, EN_SCORE  as  SCORE  from  test_tb_grade2
order  by  user_name,COURSE;

 

【转载自：http://blog.csdn.net/jx_870915876/article/details/52403472】