Question

此查询有什么问题，请告诉我。从内部查询我想根据EventID选择前1组。

请建议做什么。

SELECT TOP 1 * FROM
    (
    SELECT E.EventID, ETD.EventName, ED.EventDate FROM 
    [3rdi_EventDates] AS ED inner join [3rdi_Events] as E on ED.EventID=E.EventID 
    inner join [3rdi_EventTypeDetails] as ETD on E.EventTypeId=ETD.EventTypeId
    WHERE E.EventID in
    (
    select EventId from [3rdi_Events] WHERE
    EventID IN (select distinct EventId from [3rdi_EventDates] where EventDate Between '2/9/2011' and '3/11/2012')
    ) ORDER BY ETD.EventName, ED.EventDate  
    ) AS temp Group by EventID

Answer 1

您希望每个EventID有一条记录，在这种情况下，请使用Row_Number（）和分区。

您的两个子查询级别也不需要，内部联接涉及子查询中的两个表，因此您可以直接在主查询中进行过滤。

要做的最后一点是日期文字最好使用YYYYMMDD编写，以便对任何区域或日期格式设置都是健壮的。

SELECT EventID, EventName, EventDate
FROM (
    SELECT E.EventID, ETD.EventName, ED.EventDate,
        ROW_NUMBER() over (
            partition by E.EventID 
            ORDER BY ETD.EventName, ED.EventDate) RowNum
    FROM [3rdi_EventDates] AS ED
    inner join [3rdi_Events] as E on ED.EventID=E.EventID 
    inner join [3rdi_EventTypeDetails] as ETD on E.EventTypeId=ETD.EventTypeId
    where ED.EventDate Between '20110209' and '20120311'
    ) AS temp
WHERE RowNum = 1

Answer 2

使用此功能。

SELECT TOP 1 * FROM  (
    SELECT E.EventID, ETD.EventName, ED.EventDate FROM 
    [3rdi_EventDates] AS ED inner join [3rdi_Events] as E on ED.EventID=E.EventID 
    inner join [3rdi_EventTypeDetails] as ETD on E.EventTypeId=ETD.EventTypeId
    WHERE ED.EventDate > Convert(Datetime,'2/9/2011') and ED.EventDate < Convert(Datetime,'3/11/2012')
    ORDER BY ETD.EventName, ED.EventDate)

这个查询有什么问题？我没有得到正确的结果

2 个答案: