Oracle：按別名排序，無效標識符錯誤

Question

我收到一個奇怪的錯誤，我想我可能知道答案了，但仍然似乎無法解決。 有人說“ LatestUpdatedDate”是一個無效的標識符，我認為這是因為它在到達CASE語句之前先運行ORDER BY語句，但這對它的結構方式並沒有多大意義。 有什么想法嗎？

SELECT * FROM 
( 
  SELECT sym.*, 
    (
    CASE WHEN shr_last_updt_dt >= trd_last_updt_dt 
    THEN shr_last_updt_dt 
    ELSE trd_last_updt_dt END
    ) AS LatestUpdatedDate,
    row_number() over ( ORDER BY LatestUpdatedDate DESC ) AS line_number 
  FROM trdg_sym sym  
  WHERE ((wkly_rpt_dt = :settleDate)) AND ((lower(rpt_type_cd)=lower(:reportType)))
)  
WHERE line_number BETWEEN 1 AND 25 ORDER BY line_number

Answer 1

別名將在生成結果集后給出，因此您不能在Windowing函數中使用它們。 你可以這樣做：

SELECT * FROM 
( 
  SELECT sym.*, 
    (
    CASE WHEN shr_last_updt_dt >= trd_last_updt_dt 
    THEN shr_last_updt_dt 
    ELSE trd_last_updt_dt END
    ) AS LatestUpdatedDate,
    row_number() over ( ORDER BY 
     (
        CASE WHEN shr_last_updt_dt >= trd_last_updt_dt 
        THEN shr_last_updt_dt 
        ELSE trd_last_updt_dt END
     ) DESC ) AS line_number 
  FROM trdg_sym sym  
  WHERE ((wkly_rpt_dt = :settleDate)) AND ((lower(rpt_type_cd)=lower(:reportType)))
)  
WHERE line_number BETWEEN 1 AND 25 ORDER BY line_number

或將您的子查詢包裝到另一個

SELECT * FROM 
(
  SELECT *, 
    row_number() over ( ORDER BY LatestUpdatedDate DESC ) AS line_number 
  FROM
  (
     SELECT sym.*, 
       (
          CASE WHEN shr_last_updt_dt >= trd_last_updt_dt 
          THEN shr_last_updt_dt 
          ELSE trd_last_updt_dt END
        ) AS LatestUpdatedDate 
     FROM trdg_sym sym  
     WHERE ((wkly_rpt_dt = :settleDate)) AND ((lower(rpt_type_cd)=lower(:reportType)))
   )
)  
WHERE line_number BETWEEN 1 AND 25 ORDER BY line_number

PS：我不確定oacle語法，但是您應該給子查詢使用別名嗎？