Fix query to show what I want

Question

Hello,
I'm using Oracle JDeveloper 11g Release 2 (11.1.2.3.0).
Here a little sample data:
create table Concessionaire (CON_ID number, CON_NAME varchar2(20));
create table Stock (STO_ID number, STO_CAR_ID number, STO_CON_ID number, STO_SALE_ID number);
insert into Concessionaire values (1, 'Con1');
insert into Concessionaire values (2, 'Con2');
insert into Stock (1, 1, 1, null);
insert into Stock (2, 2, 1, null);
insert into Stock (3, 1, 2, null);
insert into Stock (4, 1, 2, null);
Query:
SELECT Concessionaire.CON_ID,
       Concessionaire.CON_NAME,
       Stock.STO_CAR_ID,
       Stock.STO_CON_ID,
       Stock.STO_ID,
       Stock.STO_SALE_ID
FROM Concessionaire, Stock
WHERE ((Concessionaire.CON_ID = Stock.STO_CON_ID) AND (Stock.STO_SALE_ID IS NULL)
Match:
CON_ID     CON_NAME     STO_ID     STO_CAR_ID     STO_CON_ID     STO_SALE_ID
    1                Con1               1                   1                       1                      null
    1                Con1               2                   2                       1                      null
    2                Con2               3                   1                       2                      null
    2                Con2               4                   1                       2                      null
And I want that the same result but without the last line. If a concessionaire have in stock the same car two times, (same STO_CAR_ID, but different STO_ID) doesn't appear in the result.
Can someone help me with this query?
Thanks in advance!           

Answer 1

WITH T AS (
           SELECT  Concessionaire.CON_ID,
                   Concessionaire.CON_NAME,
                   Stock.STO_CAR_ID,
                   Stock.STO_CON_ID,
                   Stock.STO_ID,
                   Stock.STO_SALE_ID,
                   ROW_NUMBER() OVER(PARTITION BY Concessionaire.CON_ID,Stock.STO_CAR_ID ORDER BY Stock.STO_ID) RN
             FROM  Concessionaire,
                   Stock
             WHERE Concessionaire.CON_ID = Stock.STO_CON_ID
               AND Stock.STO_SALE_ID IS NULL
SELECT  CON_ID,
        CON_NAME,
        STO_CAR_ID,
        STO_CON_ID,
        STO_ID,
        STO_SALE_ID
  FROM  T
  WHERE RN = 1
    CON_ID CON_NAME             STO_CAR_ID STO_CON_ID     STO_ID STO_SALE_ID
         1 Con1                          1          1          1
         1 Con1                          2          1          2
         2 Con2                          1          2          3
SYS@orcl >
SY.