如何在postgresql中透视联接表？

我有一张桌子 参议员： sname（键）

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party我认为您可以通过条件聚合实现这一点：

select sp.legnum,
       max(case when se.party = 'D' then se.name end) as Democrat,
       max(case when se.party = 'R' then se.name end) as Republican
from senators se join
     sponsors sp
     on sp.sname = se.sname
group by sp.legnum;

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如果您需要按参与方列出所有赞助商的列表，可以使用

array\u agg（）

或

string\u agg（）

。

请使用示例数据和所需结果编辑您的问题。

SELECT Democrat, Republican, legnum
FROM
     (select distinct sname, legnum, ROW_NUMBER() over
     (Partition By sname Order By sname) as ColumnSequence 
     from senators
     inner join sponsors
     on sponsors.sname = senators.sname)
pivot
( 
     max(sname)
     for ColumnSequence in (Democrat, Republican))
 )PIV;

select sp.legnum,
       max(case when se.party = 'D' then se.name end) as Democrat,
       max(case when se.party = 'R' then se.name end) as Republican
from senators se join
     sponsors sp
     on sp.sname = se.sname
group by sp.legnum;