SQLに存在する列の値

Question

[@myTable] .MessageId の値が存在しない場合、以下のクエリからすべてのレコードを選択したいと考えています。

DECLARE @myTable TABLE 
     (
      MessageId BIGINT , 
      RecieverId VARCHAR(100) 
     ) 



    INSERT INTO @myTable 
      (MessageId , 
       RecieverId 

      ) 
      SELECT MAX(MessageID) , 
        ReceiverID 
      FROM dbo.CM_MessageStatus 
      WHERE ReceiverID IN (SELECT * 
            FROM string_split(@UserID, ',')) 
        AND DeliveredDate IS NOT NULL 
      GROUP BY ReceiverID 

SELECT COUNT(CM_MessageStatus.MessageID) AS MessageID , 
     dbo.CM_MessageStatus.ReceiverID 
FROM dbo.CM_MessageStatus 
     LEFT JOIN @myTable ON [@myTable].RecieverId = CM_MessageStatus.ReceiverID 
           AND CM_MessageStatus.MessageID > [@myTable].MessageId 
WHERE --DeliveredDate IS NULL AND 

[@myTable] .MessageIdが0

CM_MessageStatus.MessageID > [@myTable].MessageId 
    AND ReceiverID IN (SELECT * 
         FROM string_split(@UserID, ',')) 
GROUP BY dbo.CM_MessageStatus.ReceiverID 

注それを考慮存在しない--if：[@myTable] .MessageIdが0

を考慮して存在しない場合、私は確認したいです

Answer 1

 INSERT INTO @myTable 
     (MessageId , 
      RecieverId 

     ) 
     SELECT MAX(MessageID) , 
       ReceiverID 
     FROM dbo.CM_MessageStatus 
     WHERE ReceiverID IN (SELECT * 
           FROM string_split(@UserID, ',')) 
       AND DeliveredDate IS NOT NULL 
     GROUP BY ReceiverID 

    IF @@ROWCOUNT= 0 
     insert into @myTable values(0,0) 
     select * from @mytable 
    ELSE 
     select * from @myTable