数据库：横表纵表互换
use test;
/**
* 创建表
*/
create table sales(
id int primary key auto_increment,
years year(4) not null,
month int not null,
sales int not null);
/**
* 初始化数据
*/
insert into sales(years, month, sales) values('2011', 1, 3);
insert into sales(years, month, sales) values('2011', 2, 2);
insert into sales(years, month, sales) values('2011', 3, 4);
insert into sales(years, month, sales) values('2011', 4, 1);
insert into sales(years, month, sales) values('2012', 1, 1);
insert into sales(years, month, sales) values('2012', 2, 2);
insert into sales(years, month, sales) values('2012', 3, 2);
insert into sales(years, month, sales) values('2012', 4, 3);
select * from sales;
/**
* 纵表变横表(聚合函数max/sum)
*/
select b.years,
max(case b.month when 1 then sales else 0 end) '一月',
max(case b.month when 2 then sales else 0 end) '二月',
max(case b.month when 3 then sales else 0 end) '三月',
max(case b.month when 4 then sales else 0 end) '四月'
from sales as b
group by b.years;
/**
* 纵表变横表(存储过程+ 临时表+左联结)
*/
drop procedure if exists sp_change;
drop table if exists a1,a2,a3,a4;
delimiter //
create procedure sp_change()
begin
create temporary table a1(years year(4),`一月` int) engine = Memory;
create temporary table a2(years year(4),`二月` int) engine = Memory;
create temporary table a3(years year(4),`三月` int) engine = Memory;
create temporary table a4(years year(4),`四月` int) engine = Memory;
insert into a1 select a.years, a.sales as '一月' from sales as a where a.month = 1 ;
insert into a2 select b.years, b.sales as '二月' from sales as b where b.month = 2 ;
insert into a3 select c.years, c.sales as '三月' from sales as c where c.month = 3 ;
insert into a4 select d.years, d.sales as '四月' from sales as d where d.month = 4 ;
select a1.years as year,a1.`一月`,a2.`二月`,a3.`三月`,a4.`四月`
from a1
left join a2 on a1.years = a2.years
left join a3 on a2.years = a3.years
left join a4 on a3.years = a4.years
order by a1.years;
drop table if exists a1,a2,a3,a4;
end //
delimiter ;
call sp_change();
/**
* 横表变纵表
*/
select a.years, a.sales as '一月' from sales as a where a.month = 1 union
select b.years, b.sales as '二月' from sales as b where b.month = 2 union
select c.years, c.sales as '三月' from sales as c where c.month = 3 union
select d.years, d.sales as '四月' from sales as d where d.month = 4 ;
FOR SQLSERVER(2005及更高版本)
SELECT * FROM ( SELECT 10 ids,'ab' rets UNION ALL SELECT 20 ids,'cd' rets ) bb PIVOT ( MAX(rets) FOR ids IN ([10],[20]) ) aa
欢迎点评，期待您更好的解决方案。