当表或视图具有值时，如何仅尝试 select 数据

Question

The select statement below returns no rows at the moment because sometimes A.ACCOUNT_OWNER_ID = P.PERSON_ID is false. I'm looking for a way to ONLY select the P.FIRST_NAME when these 2 fields match. If they don't I still need to select the other fields.

SELECT DISTINCT S.PRODUCT_NUMBER    AS PRODUCT_NUMBER,
       A.ACCOUNT_ID        AS ACCOUNT_ID,
       AA.COUNTRY_CODE     AS COUNTRY_CODE,
       P.FIRST_NAME        AS FIRST_NAME
       FROM VW_SUBSCRIPTION S, VW_ACCOUNT A, VW_ACCOUNT_ADDRESS AA,VW_PERSON P
       WHERE S.ACCOUNT_ID = A.ACCOUNT_ID
       AND A.ACCOUNT_OWNER_ID = P.PERSON_ID
       AND S.ACCOUNT_ID = AA.ACCOUNT_ID;

I tried doing a join like this:

SELECT DISTINCT S.PRODUCT_NUMBER AS PRODUCT_NUMBER, 
    A.ACCOUNT_ID AS ACCOUNT_ID, 
    AA.COUNTRY_CODE AS COUNTRY_CODE, 
    P.FIRST_NAME AS FIRST_NAME 
    FROM VW_SUBSCRIPTION S, VW_ACCOUNT A, VW_ACCOUNT_ADDRESS AA 
    JOIN VW_PERSON P 
    ON A.ACCOUNT_OWNER_ID = P.PERSON_ID 
    WHERE S.ACCOUNT_ID = 
    A.ACCOUNT_ID AND S.PRICE_PLAN = 'dealer' AND S.ACCOUNT_ID = 
    AA.ACCOUNT_ID;

But got this error:

ORA-00904: "A"."ACCOUNT_OWNER_ID": invalid identifier 00904. 00000 - "%s: invalid identifier" *Cause:
*Action: Error at Line: 7 Column: 17

Answer 1

I think you need a LEFT join for the table VW_PERSON , so unmatched rows will also be returned (and proper join syntax for the other tables):

SELECT DISTINCT 
       S.PRODUCT_NUMBER AS PRODUCT_NUMBER, 
       A.ACCOUNT_ID AS ACCOUNT_ID, 
       AA.COUNTRY_CODE AS COUNTRY_CODE, 
       P.FIRST_NAME AS FIRST_NAME 
FROM VW_SUBSCRIPTION S
INNER JOIN VW_ACCOUNT A ON S.ACCOUNT_ID = A.ACCOUNT_ID
INNER JOIN VW_ACCOUNT_ADDRESS AA ON S.ACCOUNT_ID = AA.ACCOUNT_ID
LEFT JOIN VW_PERSON P ON A.ACCOUNT_OWNER_ID = P.PERSON_ID 
WHERE S.PRICE_PLAN = 'dealer';

Answer 2

You would left join the table/view VW_PERSON with VW_ACCOUNT in order to get records when there are no matches between VW_PERSON and VW_ACCOUNT as follows

   SELECT DISTINCT 
          S.PRODUCT_NUMBER    AS PRODUCT_NUMBER
         ,A.ACCOUNT_ID        AS ACCOUNT_ID
         ,AA.COUNTRY_CODE     AS COUNTRY_CODE
         ,P.FIRST_NAME        AS FIRST_NAME
     FROM VW_SUBSCRIPTION S
     JOIN VW_ACCOUNT A
       ON S.ACCOUNT_ID = A.ACCOUNT_ID
     JOIN VW_ACCOUNT_ADDRESS AA
       ON S.ACCOUNT_ID = AA.ACCOUNT_ID
LEFT JOIN VW_PERSON P
      ON A.ACCOUNT_OWNER_ID = P.PERSON_ID