postgre数据库如何实现行转列

[qq_1054574015]

create table t(day date,equipment varchar(20),output integer);
insert into t values('2010-04-01','DAT501',100);
insert into t values('2010-04-01','DAT502',120);
insert into t values('2010-04-01','DAT503',130);
insert into t values('2010-04-02','DAT501',110);
insert into t values('2010-04-02','DAT502',105);
insert into t values('2010-04-03','DAT503',125);
insert into t values('2010-04-04','DAT501',100);
insert into t values('2010-04-04','DAT503',200);
--想得到如下结果
day | dat501 | dat502 | dat503
----------------+-----------+----------+--------
2010-04-01 | 100 | 120 | 130
2010-04-02 | 110 | 105 |
2010-04-03 | | | 125
2010-04-04 | 100 | | 200

[何小牛]

这个应该只能通过关联的方式解决： select t.day , t1.equipment DAT501 ,t2.equipment DAT502 ,t3.equipment DAT503 from (select distinct day from t ) t left join t t1 on t.day =t1.day and t1. equipment = 'DAT501' left join t t2 on t.day =t2.day and t2. equipment = 'DAT502' left join t t3 on t.day =t3.day and t3. equipment = 'DAT503' order by t1.day

[zeeeitch]

http://blog.csdn.net/zeeeitch/article/details/6086257

[#0xZ]

http://blog.csdn.net/post_yuan/article/details/52464004