ROW_NUMBER() VS. DISTINCT

Question

Dear All, I have a problem with ROW_NUMBER() , if i used it with DISTINCT in the following Query I have 2 scenarios: 1- run this query direct : give me for example 400 record as a result 2- uncomment a line which start with [--Uncomment1--] : give me 700 record as a result it duplicated some records not all the records

what I want is to solve this problem or to find any way to show a row counter beside each row, to make a [where rownumber between 1 and 30] --Uncomment2--

if I put the whole query in a table, and then filter it , it is work but it still so slow

waiting for any feedback and I will appreciate that

Thanks in advance

SELECT * FROM 
(SELECT Distinct  CRSTask.ID AS TaskID,
      CRSTask.WFLTaskID,
  --Uncomment1--       ROW_NUMBER() OVER (ORDER By  CRSTask.CreateDate asc ) AS RowNum ,
      CRSTask.WFLStatus AS Task_WFLStatus,
      CRSTask.Name AS StepName,
      CRSTask.ModifiedDate AS Task_ModifyDate,
      CRSTask.SendingDate AS Task_SendingDate,
      CRSTask.ReceiveDate AS Task_ReceiveDate,
      CRSTask.CreateDate AS Task_CreateDate,
      CRS_Task_Recipient_Vw.Task_CurrentSenderName,
      CRS_Task_Recipient_Vw.Task_SenderName,
      CRS_INFO.ID AS CRS_ID,
      CRS_INFO.ReferenceNumber,
      CRS_INFO.CRSBeneficiaries,

      CRS_INFO.BarCodeNumber,
      ISNULL(dbo.CRS_FNC_GetTaskReceiver(CRSTask.ID), '') + ' ' + ISNULL 

(CRS_Organization.ArName, '') 
     AS OrgName,
      CRS_Info.IncidentID,
      COALESCE(CRS_Subject.ArSubject, 'غير مبين') AS ArSubject,
      COALESCE(CRS_INFO.Subject, 'Blank Subject') AS CRS_Subject,
      CRS_INFO.Mode,
      CRS_Task_Recipient_Vw.ReceiverID,
      CRS_Task_Recipient_Vw.ReceiverType,
      CRS_Task_Recipient_Vw.CC,
      Temp_Portal_Users_View.ID AS CRS_LockedByID,
      Temp_Portal_Users_View.ArabicName AS CRS_LockedByName,
      CRSDraft.ID AS DraftID,
      CRSDraft.Type AS DraftType,
      CASE 
     WHEN CRS_Folder = 1 THEN Task_SenderName
     WHEN CRS_Folder = 2 THEN Task_SenderName
     WHEN CRS_Folder = 3 THEN Task_CurrentSenderName
      END AS SenderName,
      CRS_Task_Folder_Vw.CRS_Folder,
      CRS_INFO.Status,
      CRS_INFO.CRS_Type,
      CRS_Type.arName AS CRS_Type_Name
  FROM   CRS_Task_Folder_Vw
      LEFT OUTER JOIN CRSTask
     ON  CRSTask.ID = CRS_Task_Folder_Vw.TaskID
      LEFT OUTER JOIN CRS_INFO
     ON  CRS_INFO.ID = CRSTask.CRSID
      LEFT OUTER JOIN CRS_Subject
     ON  COALESCE(
       SUBSTRING(
        CRS_INFO.Subject,
        CHARINDEX('_', CRS_INFO.Subject) + 1,
        LEN(CRS_INFO.Subject)
       ),
       'Blank Subject'
      ) = CRS_Subject.ID
      LEFT OUTER JOIN CRSInfoAttribute
     ON  CRS_INFO.ID = CRSInfoAttribute.ID
      LEFT OUTER JOIN CRS_Organization
     ON  CRS_Organization.ID = CRSInfoAttribute.SourceID
      LEFT OUTER JOIN CRS_Type
     ON  CRS_INFO.CRS_Type = CRS_Type.ID
      LEFT OUTER JOIN CRS_Way
     ON  CRS_INFO.CRS_Send_Way = CRS_Way.ID
      LEFT OUTER JOIN CRS_Priority
     ON  CRS_INFO.CRS_Priority_ID = CRS_Priority.ID
      LEFT OUTER JOIN CRS_SecurityLevel
     ON  CRS_INFO.SecurityLevelID = CRS_SecurityLevel.ID
      LEFT OUTER JOIN Portal_Users_View
     ON  Portal_Users_View.ID = CRS_INFO.CRS_Initiator
      LEFT OUTER JOIN AD_DOC_TBL
     ON  CRS_INFO.DocumentID = AD_DOC_TBL.ID
      LEFT OUTER JOIN CRSTask AS Temp_CRSTask
     ON  CRSTask.ParentTask = Temp_CRSTask.ID
      LEFT OUTER JOIN Portal_Users_View AS Temp_Portal_Users_View
     ON  Temp_Portal_Users_View.ID = AD_DOC_TBL.Lock_User_ID
      LEFT OUTER JOIN Portal_Users_View AS Temp1_Portal_Users_View
     ON  Temp1_Portal_Users_View.ID = CRS_INFO.ClosedBy
      LEFT OUTER JOIN CRSDraft
     ON  CRSTask.ID = CRSDraft.TaskID
      LEFT OUTER JOIN CRS_Task_Recipient_Vw
     ON  CRSTask.ID = CRS_Task_Recipient_Vw.TaskID 
      --LEFT OUTER JOIN  CRSTaskReceiverUsers     ON CRSTask.ID = 

CRSTaskReceiverUsers.CRSTaskID AND CRS_Task_Recipient_Vw.ReceiverID = CRSTaskReceiverUsers.ReceiverID

      LEFT OUTER JOIN CRSTaskReceiverUserProfile
     ON  CRSTask.ID = CRSTaskReceiverUserProfile.TaskID
  WHERE  Crs_Info.SUBJECT <> 'Blank Subject'
      AND (CRS_INFO.Subject NOT LIKE '%null%')
      AND CRS_Info.IsDeleted <> 1 
       /* AND CRSTask.WFLStatus <> 6 
       AND CRSTask.WFLStatus <> 8  */
      AND (
        (
         CRS_Task_Recipient_Vw.ReceiverID IN (1, 29)
         AND CRS_Task_Recipient_Vw.ReceiverType IN (1, 3, 4)
        )
       )
      AND 1 = 1

)Codes
--Uncomment2--  WHERE Codes.RowNum BETWEEN 1 AND 30
ORDER BY
       Codes.Task_CreateDate ASC

Answer 1

If you are always starting from 1 for your range, you could always use TOP.

e.g.

SELECT TOP 30 <columns> FROM....`

Answer 2

If the issue that you have duplicate rows and DISTINCT is failing because the ordinal row number making each row unique, try (with DISTINCT):

DENSE_RANK() OVER (ORDER By CRSTask.CreateDate asc)

You can also remove the DISTINCT and GROUP BY everything in the CTE.