sql - T-SQL - 在单个表中查找 PK 的差异(自联接？)

Question

我的情况是这样的。我有一个带有“组件”的pk“父级”的产品表数据看起来像这样

Parent(PK)    Component
Car1          Wheel
Car1          Tyre
Car1          Roof
Car2          Alloy
Car2          Tyre 
Car2          Roof
Car3          Alloy
Car3          Tyre
Car3          Roof 
Car3          Leather Seats

现在我想做的是一些查询，我可以输入两个代码并查看差异... IE 如果我输入“Car1”，“Car2”，它会返回类似的内容；

Parent       Component
Car1         Wheel
Car2         Alloy

因为这是两者之间的区别。如果我说“Car1”，“Car3”，我会期待；

Parent       Component
Car1         Wheel
Car3         Alloy
Car3         Leather Seats

非常感谢您对此事的帮助。

Answer 1

没有 GROUP BY 或 UNION:

create table Products (
    Parent varchar(20) not null,
    Component varchar(20) not null
)
insert into Products (Parent,Component)
select 'Car1','Wheel' union all
select 'Car1','Tyre' union all
select 'Car1','Roof' union all
select 'Car2','Alloy' union all
select 'Car2','Tyre' union all
select 'Car2','Roof' union all
select 'Car3','Alloy' union all
select 'Car3','Tyre' union all
select 'Car3','Roof' union all
select 'Car3','Leather Seats'
go
select
    ISNULL (a.Parent,b.Parent) as Parent,
    ISNULL (a.Component,b.Component) as Component
from
    Products a
        full outer join
    Products b
        on
            a.Component = b.Component and
            a.Parent = 'Car1' and
            b.Parent = 'Car3'
where
    (a.Parent = 'Car1' and b.Parent is null) or
    (b.Parent = 'Car3' and a.Parent is null)