Question

我已经被困在这个上一段时间了。这是一个实验室，这是最后一个问题。我结合上面的查询，找到了只提供计算机的供应商。任何帮助表示赞赏。

 SELECT Name
 FROM Tb_Supplier
 WHERE Supp_ID IN
        (SELECT Supp_ID
        FROM Tb_Offers, Tb_Product
        WHERE Tb_Offers.Prod_ID = Tb_Product.Prod_ID
        AND (Tb_Product.Name = 'Computer'
          OR Tb_Product.Name = 'Truck'))
          AND Supp_ID NOT IN
            (SELECT Supp_ID
        FROM Tb_Offers, Tb_Product
        WHERE Tb_Offers.Prod_ID = Tb_Product.Prod_ID
        AND (Tb_Product.Name != 'Computer'
          OR Tb_Product.Name != 'Truck'))

我只需要找到供应计算机和卡车的供应商，而不是其他任何东西。

Answer 1

这为供应商提供了计算机和卡车，但没有别的

with dat
as
(
select 'Toronto' Supp_id,'Computer' thename union all
select 'Toronto' Supp_id,'Truck' thename union all
select 'Toronto' Supp_id,'Furniture' thename union all
select 'Ottawa' Supp_id,'Computer' thename union all
select 'Ottawa' Supp_id,'Truck' thename union all
select 'Montana' Supp_id,'Furniture' thename union all
select 'Idaho' Supp_id,'Computer' thename union all
select 'John' Supp_id,'Truck' thename union all
select 'John' Supp_id,'Furniture' thename union all
select 'Boris' Supp_id,'Computer' thename union all
select 'Boris' Supp_id,'Truck' thename union all
select 'Harold' Supp_id,'Furniture' thename union all
select 'Yelson' Supp_id,'Furniture' thename 
)
select Supp_ID from dat where thename = 'Computer'
intersect 
select Supp_ID from dat where thename = 'Truck'
except
select Supp_ID from dat where thename not in ('Truck','Computer')

Answer 2

根据您提供的内容，这是一个解决方案。

SELECT tp.name,
       ts.supp_ID
FROM Tb_Supplier ts
inner join tb_offers tb on tb.supp_id = ts.supp_id
inner join tb_prodcut tp on tp.prod_id = tb.prod_id
WHERE ts.supp_ID not in (select ts.supp_ID
                         from Tb_Supplier ts
                         inner join tb_offers tb on tb.supp_id = ts.supp_id
                         inner join tb_prodcut tp on tp.prod_id = tb.prod_id
                         where tp.product not in ('computers', 'truck')
                        )

Answer 3

这需要“关系部门”

对聚合进行分组和比较解决了许多问题，这些问题需要“仅”通过数据进行单一传递，例如

select Supp_ID 
from yourdata
group by Supp_id
having sum(case when product_name not in ('Truck','Computer') then 1 else 0 end) = 0
and min(product_name) = 'Computer'
and max(product_name) = 'Truck'
;

如果有任何其他产品，则SUM（）将是＆lt;＆gt; 0 然后min和max必须等于2个产品

替代：

select Supp_ID 
from yourdata
group by Supp_id
having sum(case when product_name not in ('Truck','Computer') then 1 else 0 end) = 0
and count(distinct product_name) = 2
;

如果有超过2种产品需要考虑，这种变体更容易修改。

请参阅：Divided We Stand: The SQL of Relational Division（Joe Celko）

仅提供卡车和计算机的供应商名称

3 个答案: