查询来获取最古老的记录

Question

我有这个下面的代码：

;with cte as (
    Select RegardingObjectId , 
      DATEADD(mi, DATEDIFF(mi, getutcdate(), getdate()),CreatedON) as [Time First Response] 
      from dbo.Email 
    where DirectionCode = '1' 
) 
SELECT dbo.Incident.new_CaseID as [CASE ID], 
     cte.RegardingObjectId, 
     dbo.Incident.IncidentId, 
     dbo.Incident.Title as [SUBJECT], 
     dbo.Incident.StatusCode as [STATUS], 
     cte.[Time First Response] 
from dbo.Incident 
left Join cte on cte.RegardingObjectId = dbo.Incident.IncidentId 
order by dbo.Incident.new_CaseID desc 

这个查询将返回类似结果：

正如你可以看到，该查询返回与同一案件ID的多个记录。我想，对于每个多个记录有相同的案例ID，只有一个最古老的[时间第一反应]检索

Answer 1

你可以用你的查询在其他CTE和使用ROW_NUMBER优先，每位[CASE ID]最早的记录：

;with cte as (
    Select RegardingObjectId , 
      DATEADD(mi, DATEDIFF(mi, getutcdate(), getdate()),CreatedON) 
      as [Time First Response] 
      from dbo.Email 
    where DirectionCode = '1' 
), cte2 as (
    SELECT dbo.Incident.new_CaseID as [CASE ID], 
      cte.RegardingObjectId, 
      dbo.Incident.IncidentId, 
      dbo.Incident.Title as [SUBJECT], 
      dbo.Incident.StatusCode as [STATUS], 
      cte.[Time First Response], 
      ROW_NUMBER() OVER (PARTITION BY dbo.Incident.new_CaseID 
           ORDER BY cte.[Time First Response]) AS rn 
    from dbo.Incident 
    left Join cte on cte.RegardingObjectId = dbo.Incident.IncidentId 
) 
SELECT [CASE ID], 
     RegardingObjectId, 
     IncidentId, 
     [SUBJECT], 
     [STATUS], 
     [Time First Response] 
FROM cte2 
WHERE rn = 1 
ORDER BY [CASE ID] desc 

Answer 2

您可以尝试使用MIN功能

;with cte as (
    Select RegardingObjectId , 
      DATEADD(mi, DATEDIFF(mi, getutcdate(), getdate()),CreatedON) as [Time First Response] 
      from dbo.Email 
    where DirectionCode = '1' 
) 
SELECT dbo.Incident.new_CaseID as [CASE ID], 
     cte.RegardingObjectId, 
     dbo.Incident.IncidentId, 
     dbo.Incident.Title as [SUBJECT], 
     dbo.Incident.StatusCode as [STATUS], 
     cte.[Time First Response] 
from dbo.Incident 
left Join cte on cte.RegardingObjectId = dbo.Incident.IncidentId 
AND cte.[Time First Response] IN (SELECT MIN(cte.[Time First Response]) 
FROM cte WHERE cte.RegardingObjectId = dbo.Incident.IncidentId) 
order by dbo.Incident.new_CaseID desc