Oracle SQL Self-Join：如何包括丢失的记录

Question

I want to display the NAME and PLAN even if they are no records. I tried to use self join on this one but no luck :(

script:

    SELECT DISTINCT    A.NAME  , B.PLAN
    FROM PLAYER A  
    LEFT JOIN PLAYER B
    ON A.NAME = B.NAME 
    WHERE A.NAME IN ( 'BOGGIE', 'STEPH')
    AND  B.PLAN IN ('PLAN200' , 'PLAN999');

current result

    NAME    PLAN
    BOOGIE  PLAN200
    STEPH   PLAN200

expected result

    NAME    PLAN
    BOOGIE  PLAN200
    BOOGIE  
    STEPH   PLAN200
    STEPH   

TABLE

    NAME    PLAN    AMOUNT  CONTRACT
    BOGGIE  PLAN200   200      24
    STEPH   PLAN200   200      24

Answer 1

You can try using put your other condition in ON clause

SELECT DISTINCT    A.NAME  , B.PLAN
    FROM PLAYER A  
    LEFT JOIN PLAYER B
    ON A.NAME = B.NAME 
    and A.NAME IN ( 'BOGGIE', 'STEPH')
    AND  B.PLAN IN ('PLAN200' , 'PLAN999');

Answer 2

The problem with the query is:

A.NAME IN ( 'BOGGIE', 'STEPH') AND B.PLAN IN ('PLAN200' , 'PLAN999');

The query is putting a left join on NAME , but the records are getting further filtered after the left join has been applied. The where clause conditions should be correctly added in left join clause.

Below query should give the expected result.

SELECT DISTINCT    A.NAME  , B.PLAN
FROM PLAYER A 
LEFT JOIN PLAYER B
ON A.NAME = B.NAME
AND (A.NAME IN ( 'BOGGIE', 'STEPH')
OR B.PLAN IN ('PLAN200' , 'PLAN999'));

Answer 3

The sample data in the question is incomplete to have the desired output; please try the below. Added two rows for BOGGIE and STEPH with null plans; let us know this suffices.

WITH player
     AS (SELECT 'BOGGIE' name,
                'PLAN200' plan,
                200 amount,
                24 contract
           FROM DUAL
         UNION
         SELECT 'STEPH ' name,
                'PLAN200' plan,
                200 amount,
                24 contract
           FROM DUAL
         UNION
         SELECT 'BOGGIE' name,
                NULL plan,
                NULL amount,
                NULL contract
           FROM DUAL
         UNION
         SELECT 'STEPH ' name,
                NULL plan,
                NULL amount,
                NULL contract
           FROM DUAL)
SELECT DISTINCT a.name, b.plan
  FROM player a
       LEFT OUTER JOIN player b
          ON     a.name = b.name
             AND (   a.name IN ('BOGGIE', 'STEPH')
                  OR b.plan IN ('PLAN200', 'PLAN999')) 

Output

NAME   PLAN   
------ -------
BOGGIE PLAN200
BOGGIE        
STEPH  PLAN200
STEPH 

Answer 4

First cross join the PLAYER with the two plans --> cross_result. Once you get that you would have result set as follows

cross_result
BOOGIE PLAN200
BOOGIE PLAN999
STEPH  PLAN200
STEPH  PLAN999

player
BOOGIE PLAN200
STEPH  PLAN200

After that left join cross_result with the PLAYER table

with cte
      as (SELECT 'PLAN200' as plan FROM DUAL
           UNION ALL
          SELECT 'PLAN999' as plan FROM DUAL
          )
    ,cross_result  
     as (select A.PLAYER,A.PLAN
           from cte m
           join PLAYER A
             ON A.NAME IN ( 'BOGGIE', 'STEPH')
         )
   select a.PLAYER,b.PLAN /*I have choosen b.PLAN, so for a.PLAN=PLAN99 it would display null*/
     from cross_result a
left join PLAYER b
       on a.player=b.player
      and a.plan=b.plan