左外连接缺少记录

Question

I am trying to list the missing records in my PartsOnHand. If my inventory table lists an item and it is not related to my PartsOnHand I want to list out which items are missing for each records.

Here is the query I tried using:

select * 
from inventory i
left outer join PartsOnHand ph on  i.InName = ph.InName 

My table structure is as follows:

Inventory:

InName
-----------
Wrench
Hammer 
Pen

PartsOnHand:

id    Inname
------------------
505   Hammer 
505   Wrench
501   Wrench
501   Hammer 

Desired Results:

505   Pen
501   Pen

---

Sample Data:

Select *
    FROM (
with inventory as (
    select 'Wrench' as InName from dual
    union 
    select 'Hammer' from dual
    union 
    select 'Pen' from dual

    ), partsonhand as (
    select '505' as id, 'Wrench' InName  from dual
    union  
    select '505' as id, 'Hammer' InName from dual
    union 
    select '501' as id, 'Wrench' InName from dual
    union 
    select '501' as id, 'Hammer' InName from dual
    )
    select * 
    from inventory i
    left outer join PartsOnHand ph on  i.InName = ph.InName 

    )

Answer 1

Either you have an additional table ALL_ID with a column ID (primary key, and column id in PartsOnHand pointing to it), which would be the proper setup; OR you want the ID's to be read from table PartsOnHand. I will assume the former; if it's the latter, ALL_ID can be created as a subquery, by selecting distinct id from PartsOnHand

select id, inname
from   all_id cross join inventory
where  (id, inname) not in (select id, inname from partsonhand)
;

This assumes there are no NULLS in PartsOnHand (there shouldn't be any - otherwise you have data problems).

Answer 2

You can do this by creating all of the different possible combinations of Id and InName via a CROSS JOIN and doing a RIGHT JOIN to that result:

Select  L.*
From    PartsOnHand P
Right Join
(
    Select  Id, InName
    From    Inventory   I
    Cross Join
    (
        Select  Distinct Id
        From    PartsOnHand P
    ) X
) L On  L.id = P.id
    And L.InName = P.InName
Where   P.id Is Null

Results:

Id  InName
501 Pen
505 Pen

Answer 3

Seems odd to assign the same IDs to different names... (How do I know the ID of Pen is 505 and 501?) but this delivers the desired results in example:

with inventory as (
select 'Wrench' as InName from dual
union 
select 'Hammer' from dual
union 
select 'Pen' from dual

), partsonhand as (
select '505' as id, 'Wrench' InName  from dual
union  
select '501' as id, 'Hammer' InName from dual
union 
select '505' as id, 'Wrench' InName from dual
union 
select '501' as id, 'Hammer' InName from dual
)
select C.ID, I.InName 
from inventory i
LEFT join partsonhand P
 on I.Inname = P.InName
cross join (Select distinct ID from partsonHand) C
Where P.ID is null
order by ID Desc;