从一个sql结果集加入数据

Question

我正在使用MS SQL server 2012。

我有以下查询

Select HedgeDate, CompanyName, HedgeValue 
FROM GasHedges
LEFT OUTER JOIN GasCompanies ON GasHedges.CompanyID = GasCompanies.ID
WHERE HedgeDate BETWEEN '2014-09-01' AND '2014-09-05'

返回

我想以下列格式显示它。

我整个上午一直在努力，并没有真正到达那里。我不想在SQL代码中指定companyName，因为可以将更多公司添加到表中。我一直在尝试不同的连接变体，但没有到达任何地方。我也在看工会，但似乎无法得到它。

非常感谢任何帮助。

Answer 1

SELECT HedgeDate, CompanyName, HedgeValue 
FROM GasHedges
LEFT OUTER JOIN GasCompanies ON GasHedges.CompanyID = GasCompanies.ID
PIVOT (count(HedgeValue) FOR CompanyName in ([RWET], [JPMorgan], [Statoil]))
WHERE HedgeDate BETWEEN '2014-09-01' AND '2014-09-05'

你去吧

编辑1，

如果您希望列表是动态的，请参阅HERE 尝试自己动手以确保理解

Answer 2

感谢ah_hau，在你的指导下，我得到了以下代码

DECLARE @StartDate date
DECLARE @EndDate date
DECLARE @cols nvarchar(2000)
DECLARE @query nvarchar(3000)

select  @cols = coalesce(@cols + ',[' + companyName + ']', '[' + companyName + ']')
from GasCompanies
set @query = 'select *
from
(Select HedgeDate, CompanyName, HedgeValue 
FROM GasHedges
LEFT OUTER JOIN GasCompanies ON GasHedges.CompanyID = GasCompanies.ID
WHERE HedgeDate BETWEEN DATEADD(month, DATEDIFF(month, 0, GETDATE()), 0) AND dateadd(month,1+datediff(month,0,getdate()),-1)) as s
PIVOT
(
count(HedgeValue) FOR CompanyName in ( '+@cols +' )

)  as t'

execute(@query)