- 有report表:它里面 id name state customerid 四个字段,id为主键 ,customerid为外键
- state 0, 1,2 // 未使用 更新 删除
- 根据customerid写一条sql (注意是一条)生成表的结构如下:
- customerid state0 state1 state2
- 001 11 212 333
- 002 15 545 3
实际上把它看作:select costomerid,count() as status_0,...
from report
group by costomerid
select customerid, count(case state when 0 then state else null end) as status_0, count(case state when 1 then state else null end) as status_1, count(case state when 2 then state else null end) as status_2 from report group by customerid
创建表:
create table report ( id int(10) not null auto_increment, username VARCHAR(20), state int(10), customerid int(10), PRIMARY KEY(id) ) insert into report(username,state,customerid) VALUES ('linux1',0,1), ('linux2',1,1), ('linux3',2,1), ('linux4',0,1), ('linux5',1,1), ('linux6',2,1), ('linux7',2,1), ('linux8',2,1), ('linux1',0,2), ('linux2',2,2), ('linux3',2,2), ('linux4',2,2), ('linux5',1,2), ('linux6',2,2), ('linux7',2,2), ('linux8',2,2), ('linux1',0,3), ('linux2',1,3), ('linux3',2,3), ('linux4',0,3), ('linux5',1,3), ('linux6',2,3), ('linux7',2,3), ('linux8',2,3), ('linux1',2,3), ('linux2',2,3), ('linux3',2,3), ('linux4',0,3), ('linux5',1,3), ('linux6',2,1), ('linux7',1,1), ('linux8',1,1);