テーブル変数 CTE に挿入

これを試してください

with CTE as 
    (SELECT       
      a.Title 
     ,a.Id
  FROM
       TableA
     )
    ,CTE2 as 
    (SELECT  
      b.Title
     ,b.Id   
  FROM
       TableB
    )
    INSERT INTO @myData  --- insert statement goes here after CTE

    Select * From CTE    
    union all    
    Select * From CTE2

    Select  ROW_NUMBER() OVER(ORDER BY GetDate() DESC) AS RowId, x.* 
    From @myData x
    order by x.Id desc