Question

我遇到了类似的问题，I had a couple of months ago：我需要从子查询中返回一个值，该子查询可能会也可能不会返回值列表。因此，我首先应用ORDER BY并选择带有WHERE ROWNUM=1的最顶层条目然后（是的，我在Oracle上）。

问题是，由于嵌套，内部查询中所需的ID未知。

上次，我被建议使用Oracles分析函数并应用MIN() / MAX()。但是，这次我选择货币符号（VARCHAR）并且无法使用这些功能。

非常感谢任何帮助。这是我的查询的相关部分：

SELECT
  MyOtherColumn,

  (SELECT CurrencySymbol FROM (
     SELECT DISTINCT P2.ID, P2.VALIDFROMDATE, CURR.CURRENCYSYMBOL AS CurrencySymbol FROM MY_ORDER_TABLEPOS OP2
     JOIN MY_ORDER_TABLE O2 ON OP2.FK_ORDER=O2.ID
     JOIN MY_PRICE_TABLE P2 ON OP2.FK_CONCRETARTICLE=P2.FK_ARTICLE
     JOIN MY_CURRENCY_TABLE CURR ON P2.FK_CURRENCY=CURR.ID
     WHERE OP2.FK_ORDER=O.ID AND P2.ID=( -- This fails, since O.ID is unknown in inner query!
       -- Determine current price for article
       SELECT MAX(P3.ID) KEEP (DENSE_RANK FIRST ORDER BY P3.MINTOORDER DESC, P3.VALIDFROMDATE DESC) CurrentPriceId
       FROM MY_PRICE_TABLE P3
       WHERE P3.FK_ARTICLE=OP2.FK_CONCRETARTICLE
       AND P3.VALIDFROMDATE<=SYSDATE
       AND P3.MINTOORDER<=OP2.AMOUNT
     )
     ORDER BY P2.VALIDFROMDATE DESC
  )
  WHERE ROWNUM=1) CurrencySymbol

FROM ...
WHERE O.ID=786;

向内部查询添加ID

SELECT DISTINCT P2.ID, P2.VALIDFROMDATE, CURR.CURRENCYSYMBOL AS CurrencySymbol FROM MY_ORDER_TABLEPOS OP2
JOIN MY_ORDER_TABLE O2 ON OP2.FK_ORDER=O2.ID
JOIN MY_PRICE_TABLE P2 ON OP2.FK_CONCRETARTICLE=P2.FK_ARTICLE
JOIN MY_CURRENCY_TABLE CURR ON P2.FK_CURRENCY=CURR.ID
WHERE OP2.FK_ORDER=786 AND P2.ID=( -- ID was set statically here
 -- Determine current price for article
 SELECT MAX(P3.ID) KEEP (DENSE_RANK FIRST ORDER BY P3.MINTOORDER DESC, P3.VALIDFROMDATE DESC) CurrentPriceId
 FROM MY_PRICE_TABLE P3
 WHERE P3.FK_ARTICLE=OP2.FK_CONCRETARTICLE
 AND P3.VALIDFROMDATE<=SYSDATE
 AND P3.MINTOORDER<=OP2.AMOUNT
)
ORDER BY P2.VALIDFROMDATE DESC;

得到了我的结果：

ID     VALIDFROMDATE                  CURRENCYSYMBOL
597    18.11.14 00:00:00,000000000    $
556    10.11.14 10:54:05,973000000    €
552    10.11.14 10:44:25,719000000    €
258    15.10.14 10:12:01,670000000    €

我的目标是返回最顶层条目的CURRENCYSYMBOL（此处：$）。

所以，我的问题是：如何将订单ID传递给嵌套查询，或者如何重写查询以满足我的需求？我知道查询过于复杂，我为此道歉。：）

Answer 1

  (SELECT CurrencySymbol FROM (
     SELECT OP2.FK_ORDER, CURR.CURRENCYSYMBOL AS CurrencySymbol,
            ROW_NUMBER() OVER(PARTITION BY OP2.FK_ORDER ORDER BY P2.VALIDFROMDATE DESC) RW
     FROM MY_ORDER_TABLEPOS OP2
         JOIN MY_ORDER_TABLE O2 ON OP2.FK_ORDER=O2.ID
         JOIN MY_PRICE_TABLE P2 ON OP2.FK_CONCRETARTICLE=P2.FK_ARTICLE
         JOIN MY_CURRENCY_TABLE CURR ON P2.FK_CURRENCY=CURR.ID
     WHERE P2.ID=(
       -- Determine current price for article
       SELECT MAX(P3.ID) KEEP (DENSE_RANK FIRST ORDER BY P3.MINTOORDER DESC, P3.VALIDFROMDATE DESC) CurrentPriceId
       FROM MY_PRICE_TABLE P3
       WHERE P3.FK_ARTICLE=OP2.FK_CONCRETARTICLE
       AND P3.VALIDFROMDATE<=SYSDATE
       AND P3.MINTOORDER<=OP2.AMOUNT
     )
  )
  WHERE FK_ORDER = O.ID AND RW=1) CurrencySymbol

使用ORDER BY和ROWNUM将id传递给嵌套查询的内部SELECT

1 个答案: