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将行转换为允许重复的列

calculated-columns crosstab rows postgresql sql

Gothmog · 技术社区 · 16 年前

考虑下表和行:

清单A。

ID, name, event, type
1, 'John Doe', '2010-09-01 15:00:00.000', 'input'
1, 'John Doe', '2010-09-03 11:00:00.000', 'input'
1, 'John Doe', '2010-09-04 17:00:00.000', 'input'
1, 'John Doe', '2010-09-02 15:00:00.000', 'output'
1, 'John Doe', '2010-09-03 16:00:00.000', 'output'
1, 'John Doe', '2010-09-06 17:00:00.000', 'output'

我想要的是将行转换为列,这样就可以有两个不同的列,input event和output event。比如:

清单B。

ID, name, input event, output event
1, 'John Doe', '2010-09-01 15:00:00.000', '2010-09-02 15:00:00.000'
1, 'John Doe', '2010-09-03 11:00:00.000', '2010-09-03 16:00:00.000'
1, 'John Doe', '2010-09-04 17:00:00.000', '2010-09-06 17:00:00.000'

我得到了如下结果:

清单C。

ID, name, input event, output event
1, 'John Doe', '2010-09-01 15:00:00.000', null
1, 'John Doe', '2010-09-03 11:00:00.000', null
1, 'John Doe', '2010-09-04 17:00:00.000', null
1, 'John Doe', null, '2010-09-02 15:00:00.000'
1, 'John Doe', null, '2010-09-03 16:00:00.000'
1, 'John Doe', null, '2010-09-06 17:00:00.000'

,但问题是如何平铺行,因为重复的元组ID名称是相关的。要将行转换为列,我通常编写如下代码:

select ID, name, max(case when type = 'input' then event else null end) as 'input event', max(case when type = 'output' then event else null end) as 'output event' from events group by ID, name

当然,组员会去掉重复的,这是我不想要的。

有没有办法通过查询来实现这一点?

如果有一个可移植的sql解决方案或postgresql,那就太好了,但是任何想法都是非常感谢的。

3 回复 | 直到 16 年前

user359040 user359040 16 年前

select ID, name, event as 'input event', 
       (select min(o.event) 
        from events o 
        where o.type = 'output' and 
              i.ID = o.ID and 
              i.name = o.name and 
              i.event < o.event) as 'output event' 
from events i
where i.type = 'input'
group by ID, name, event

bluish dmajkic 15 年前

select t1.id,t1.name,t1.event,t2.event from test t1
    inner join test t2 on t1.event <= t2.event 
        and t1.type = 'input' 
        and t2.type = 'output'
                   and t1.id = t2.id
                   and t1.name = t2.name

问题是您需要以某种方式链接输入/输出会话。在这个查询中,我使用timestamp事件列来完成它。如果这不是你想要的,你能提供更多的信息吗?

更新: 现在,你可以做一些后期处理

with a as
(
select t1.id,t1.name,t1.event as in_event,t2.event as out_event from test t1
    inner join test t2 on t1.event <= t2.event 
                   and t1.type = 'input' 
                   and t2.type = 'output'
                   and t1.id = t2.id
                   and t1.name = t2.name
)
select id,name,in_event,min(out_event)
       from a
group by id,name,in_event

Burcin 16 年前

create table #a(
ID int,
name varchar(30),
event datetime,
type varchar(10)
)

insert #a
select  
1, 'John Doe', '2010-09-01 15:00:00.000', 'input'
union select 1, 'John Doe', '2010-09-01 16:00:00.000', 'input'
union select 1, 'John Doe', '2010-09-01 17:00:00.000', 'input'
union select 1, 'John Doe', '2010-09-02 15:00:00.000', 'output'
union select 1, 'John Doe', '2010-09-02 16:00:00.000', 'output'
union select 1, 'John Doe', '2010-09-02 17:00:00.000', 'output'

select 
    ID, 
    name, 
    case when type = 'input' then event else null end "input event",
    case when type = 'output' then event else null end "output event"
 from #a