左外连接缺少记录

Question

我试图在我的PartsOnHand中列出缺少的记录。 如果我的库存表列出了一个项目，但它与我的PartsOnHand没有关系，我想列出每个记录中缺少的项目。

这是我尝试使用的查询：

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

我的表结构如下：

库存：

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

零件：

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

所需结果：

505   Pen
501   Pen

---

样本数据：

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

您可能还有一个带有列ID（主键，PartsOnHand中的列ID指向它）的附加表ALL_ID，这是正确的设置。 或者，您希望从表PartsOnHand中读取ID。 我假设是前者； 如果是后者，则可以通过从PartsOnHand中选择不同的ID将ALL_ID创建为子查询。

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

这假设在PartsOnHand中没有NULL（不应有NULL-否则会出现数据问题）。

Answer 2

您可以通过CROSS JOIN创建Id和InName所有可能的不同组合，并对InName进行RIGHT JOIN来做到这一点：

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

结果：

Id  InName
501 Pen
505 Pen

Answer 3

将相同的ID分配给不同的名称似乎很奇怪...（我怎么知道Pen的ID是505和501？），但是在示例中可以达到预期的效果：

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;