Oracle：按别名排序，无效标识符错误

Question

我收到一个奇怪的错误，我想我可能知道答案了，但仍然似乎无法解决。 有人说“ LatestUpdatedDate”是一个无效的标识符，我认为这是因为它在到达CASE语句之前先运行ORDER BY语句，但这对它的结构方式并没有多大意义。 有什么想法吗？

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

别名将在生成结果集后给出，因此您不能在Windowing函数中使用它们。 你可以这样做：

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

或将您的子查询包装到另一个

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：我不确定oacle语法，但是您应该给子查询使用别名吗？