SELECT A.* 
  FROM (SELECT ROW_NUMBER() OVER(ORDER BY SystemId asc) AS RowNum,
               S.SystemId   AS SystemId,
               S.SystemName AS SystemName,
               S.SystemDesc AS SystemDesc,
               COALESCE(CONVERT(CHAR(19), S.CreatedAt, 120), '-') AS CreatedAt,
               (SELECT COUNT(1) FROM TB_LINKED_SERVER WHERE SystemId = S.SystemId AND UseYn = 1) AS ServerCount
          FROM TB_LINKED_SYSTEM S WHERE UseYn = 1
        ) A
  WHERE RowNum BETWEEN @startRow AND @endRow