MySQL横纵表相互转化操作实现方法

本文实例讲述了mysql横纵表相互转化操作实现方法。分享给大家供大家参考，具体如下：

先创建一个成绩表（纵表）

create table user_score
(
  name varchar(20),
  subjects varchar(20),
  score int
);
insert into user_score(name,subjects,score) values('张三','语文',60);
insert into user_score(name,subjects,score) values('张三','数学',70);
insert into user_score(name,subjects,score) values('张三','英语',80);
insert into user_score(name,subjects,score) values('李四','语文',90);
insert into user_score(name,subjects,score) values('李四','数学',100);

再创建一个成绩表（横表）

create table user_score2
(
  name varchar(20),
  yuwen int,
  shuxue int,
  yingyu int
);
insert into user_score2(name,yuwen,shuxue,yingyu) values('张三',60,70,80);
insert into user_score2(name,yuwen,shuxue,yingyu) values('李四',90,100,0);

纵表转横表

select name,sum(case subjects when '语文' then score else 0 end) 
as '语文',sum(case subjects when '数学' then score else 0 end) 
as '数学', sum(case subjects when '英语' then score else 0 end) 
as '英语'from user_score group by name;

纵表转横表

select  name,'yuwen'  as   subjects,yuwen  as  score  from  user_score2  union  all  
select  name,'shuxue'  as   subjects,shuxue  as  score  from  user_score2 union  all  
select  name,'yingyu'  as   subjects,yingyu  as  score  from  user_score2 
order by name,subjects desc;