Mysql行转列

准备表数据

CREATE TABLE test_user (  
  name varchar(50) DEFAULT NULL,  
  subject varchar(50) DEFAULT NULL,  
  score int(11) DEFAULT NULL  
);  
insert into test_user values  
('zhangsan' , 'chinese' , 10),  
('zhangsan' , 'math' , 20),  
('zhangsan' , 'english' , 30),  
('lily' , 'chinese' , 40),  
('lily' , 'math' , 50),  
('lily' , 'english' , 60),  
('mini' , 'chinese' , 70),  
('mini' , 'math' , 80),  
('mini' , 'english' , 90);  
  
select * from test_user  

行转列

select name,  
 max(IF(subject = 'chinese',score,0)) as 'chinese',  
 max(IF(subject = 'math',score,0)) as 'math',  
 max(IF(subject = 'english',score,0)) as 'english',  
 sum(score) as'total'  
from test_user  
group by name  

分析执行计划：
1、对表中数据根据name进行分组
2、对分组后的数据，进行处理。