1

我试图了解在我的查询中对最外层选择使用 DISITINCT 时使用 row_number() 函数按降序排序结果时看到的异常行为，如下所示： 

 SELECT   DISTINCT (ID), State_Id, Name_Of_Trip, Date_Of_Travel, Creation_Date, Locking_Id, Applicant_Name, Reference_Number, State_Name
    FROM (

    SELECT  app.ID, app.State_Id, app.Name_Of_Trip, app.Date_Of_Travel, app.Creation_Date, app.Locking_Id, app.Applicant_Name, app.Reference_Number, 
    State.Name AS State_Name, ROW_NUMBER() OVER(ORDER BY Reference_Number DESC) as rowNum  
    FROM Application_Leg AS app 
    INNER JOIN State AS state 
    ON app.State_Id = state.ID
    WHERE  (app.State_Id = 5 OR app.State_Id = 6 OR app.State_Id = 8)  AND app.Organisation_Id=12 
    AND Leg_Number IN
     (SELECT  DISTINCT Leg_Number 
     from Application_Leg as al
     INNER JOIN
     Organisation as org
     ON al.Organisation_Id = org.ID
     WHERE al.ID=app.ID AND org.Approval_Required=1 AND Mode_Of_Transport=1))
     as pagedApplications
    WHERE rowNum BETWEEN 0 AND (0 + 10)

当最外面的 DISTINCT 被取出时，降序是可以的，但是当它被包含时，结果不会以降序显示。

4

2 回答 2

9

ORDER BYinROW_NUMBER子句不保证结果集的顺序。

ROW_NUMBER通常在查询计划中使用排序，这会导致值预先排序。

这是一个副作用，不应依赖。

DISTINCT使用Hash Match (Aggregate)破坏排序。

在查询末尾添加ORDER BY子句：

SELECT  DISTINCT (ID), State_Id, Name_Of_Trip, Date_Of_Travel, Creation_Date, Locking_Id, Applicant_Name, Reference_Number, State_Name
FROM    (
        SELECT  app.ID, app.State_Id, app.Name_Of_Trip, app.Date_Of_Travel,
                app.Creation_Date, app.Locking_Id, app.Applicant_Name, app.Reference_Number, 
                State.Name AS State_Name, ROW_NUMBER() OVER(ORDER BY Reference_Number DESC) as rowNum  
        FROM    Application_Leg AS app 
        INNER JOIN
                State AS state 
        ON      app.State_Id = state.ID
        WHERE   app.State_Id IN (5, 6, 8)
                AND app.Organisation_Id = 12 
                AND Leg_Number IN
                (
                SELECT  Leg_Number 
                FROM    Application_Leg as al
                INNER JOIN
                        Organisation as org
                ON      al.Organisation_Id = org.ID
                WHERE   al.ID = app.ID
                        AND org.Approval_Required = 1
                        AND Mode_Of_Transport = 1
                )
        ) AS pagedApplications
WHERE   rowNum BETWEEN 0 AND (0 + 10)
ORDER BY
        ReferenceNumber DESC

另请注意，它不会返回10不同的结果，它将返回DISTINCT第一个10结果。

如果你想要前者，使用这个：

SELECT  DISTINCT TOP 10 ID, State_Id, Name_Of_Trip, Date_Of_Travel, Creation_Date, Locking_Id, Applicant_Name, Reference_Number, State_Name
FROM    (
        SELECT  app.ID, app.State_Id, app.Name_Of_Trip, app.Date_Of_Travel,
                app.Creation_Date, app.Locking_Id, app.Applicant_Name, app.Reference_Number, 
                State.Name AS State_Name
        FROM    Application_Leg AS app 
        INNER JOIN
                State AS state 
        ON      app.State_Id = state.ID
        WHERE   app.State_Id IN (5, 6, 8)
                AND app.Organisation_Id = 12 
                AND EXISTS
                (
                SELECT  Leg_Number 
                FROM    Application_Leg AS al
                INNER JOIN
                        Organisation as org
                ON      al.Organisation_Id = org.ID
                WHERE   al.ID = app.ID
                        AND al.LegNumber = app.LegNumber
                        AND org.Approval_Required = 1
                        AND Mode_Of_Transport = 1
                )
        ) AS pagedApplications
ORDER BY
        ReferenceNumber DESC
于 2009-09-24T14:07:06.253 回答
0

您是否尝试将 order by 添加到您的外部选择？

于 2009-09-24T14:06:53.493 回答