Question

我有两个需要合并的选择查询....

  SELECT [DatapointID]
  ,[AssetID]
  ,[DatapointID]
  ,[SourceTag]
  ,'-' + [TimeStep] + [TimeStepValue] AS TimeStep
  ,[DataRetrievalInterval] + [DataRetrievalIntervalValue] AS [RetInterval]
  ,NULL AS DatapointDate
  ,NULL AS DatapointValue
  ,0 As DataFlagID
  ,DateADD(-1, d @SearchDateEnd) + @SearchTimeEnd DateDataGrabbed
  ,GetDate() DateTimeAddedtoDB
FROM [dbo].[tblTSS_Assets_Datapoints]
Where AssetID = 204     


Select DatapointDate, SUM(DataPointValue) as DataPointValue From @temp
GROUP BY DatapointDate
ORDER BY DatapointDate

第一个选择查询是我想要的最终结果然而不是NULL作为DatapointDate和DatapointValue我想要来自@temp的值

我该怎么做？

Answer 1

连接将合并两个表中的值。在这种情况下，没有明显的连接键，因此您将有一个交叉连接：

SELECT [DatapointID], [AssetID], [DatapointID], [SourceTag],
       '-' + [TimeStep] + [TimeStepValue] AS TimeStep,
       [DataRetrievalInterval] + [DataRetrievalIntervalValue] AS [RetInterval],
       d.DatePointDate, d.DatapointValue,
       0 As DataFlagID,
       DateADD(-1, d @SearchDateEnd) + @SearchTimeEnd DateDataGrabbed,
       GetDate() DateTimeAddedtoDB
FROM [dbo].[tblTSS_Assets_Datapoints] cross join
     (Select DatapointDate, SUM(DataPointValue) as DataPointValue From @temp
      GROUP BY DatapointDate
     ) d
Where AssetID = 204

然而，这将乘以行数，每个日期一行。您是否有选择其中一行的具体规则？

一起加入两个选择查询

1 个答案: