甲骨文空值問題與

組我下面的查詢：甲骨文空值問題與

SELECT EMAIL.MAILADDRESS, COUNT (DISTINCT CUSTOMER.CUSTOMER_ID) distinct_count 
    FROM ( SELECT CUSTOMER_ID, 
         TRUNC (MAX (UPDATE_DATE)) AS UPDATE_TARIHI, 
         TRUNC (MIN (INSERT_DATE)) AS DATA_ENTRY_DATE, 
         'YES' AS MAILADDRESS 
       FROM ELECTRONIC_ADDRESS 
       WHERE ADDRESS_TYPE = 'ELECTRONIC' 
      GROUP BY CUSTOMER_ID) EMAIL 
     RIGHT OUTER JOIN 
      CUSTOMER 
     ON (EMAIL.CUSTOMER_ID = CUSTOMER.CUSTOMER_ID) 
GROUP BY EMAIL.MAILADDRESS

我加入電子郵件（子查詢-incoludes「E」 AS MAILADDRESS）和客戶表。有些客戶不具有的emailadress所以我認爲結果應該是像belowe條款：

MAILADDRESS  DISTINCT_COUNT 
YES      158945 
NULL      76345

但是當我運行此查詢時，只顯示第一行（其電子郵件地址是YES）

如果我將EMAIL.MAILADDRESS子句更改爲選定列中的nvl（EMAIL.MAILADDRESS，「否」）並逐個分組，查詢運行完美。但我無法解決問題，因爲該查詢是從Business Objects Universe生成的，所以我無法更改該查詢。

我們寫這個部分：

SELECT CUSTOMER_ID, 
        TRUNC (MAX (UPDATE_DATE)) AS UPDATE_TARIHI, 
        TRUNC (MIN (INSERT_DATE)) AS DATA_ENTRY_DATE, 
        'YES' AS MAILADDRESS 
      FROM ELECTRONIC_ADDRESS 
      WHERE ADDRESS_TYPE = 'ELECTRONIC' 
     GROUP BY CUSTOMER_ID

，然後構建一個合適的加入這個部分和客戶表之間的關係。

我該如何解決問題？爲什麼Oracle不顯示空值？

來源

2011-07-27 jerfi

你說你加入這個查詢

select customer_id 
     ,trunc(max(update_date)) as update_tarihi 
     ,trunc(min(insert_date)) as data_entry_date 
     ,'YES' as mailaddress 
    from electronic_address 
    where address_type = 'ELECTRONIC' 
    group by customer_id

客戶表。這並不意味着你只會得到有電子郵件地址的記錄（='YES'）？

來源

2011-07-27 13:30:32 Rene

如果你看一下在第一個查詢後，你會看到這個部分在「右外連接」的左側。 – Allan

使用以下SQL，我無法重新創建您的問題。

CREATE TABLE a1 (a NUMBER); 

CREATE TABLE a2 (a NUMBER); 

INSERT INTO a1 
    SELECT  LEVEL 
    FROM  DUAL 
    CONNECT BY LEVEL <= 10; 

INSERT INTO a2 
    SELECT  LEVEL 
    FROM  DUAL 
    CONNECT BY LEVEL <= 20; 

SELECT a1.a, COUNT(DISTINCT a2.a) 
FROM  a1 RIGHT OUTER JOIN a2 ON a1.a = a2.a 
GROUP BY a1.a;

這表明問題出在數據上，而不是SQL。如果客戶沒有電子郵件地址，那麼在ELECTRONIC_ADDRESS表中仍有記錄，但其他列是空的，是否有可能？

如果是這樣的話，我會如下改變你的子查詢（其中，「地址」是包含電子郵件地址的實際列）：

SELECT CUSTOMER_ID, 
      TRUNC (MAX (UPDATE_DATE)) AS UPDATE_TARIHI, 
      TRUNC (MIN (INSERT_DATE)) AS DATA_ENTRY_DATE, 
      CASE WHEN ADDRESS IS NULL 
       THEN NULL 
       ELSE 'YES' 
       END AS MAILADDRESS 
    FROM ELECTRONIC_ADDRESS 
    WHERE ADDRESS_TYPE = 'ELECTRONIC' 
GROUP BY CUSTOMER_ID

來源

2011-07-27 13:50:38 Allan

甲骨文空值問題與

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