Question

我希望购买产品X和Y和Z的customerid来自以下架构：

销售（customerid，productName， rid ）;

我可以做交集：

select customerid from sales where productName='X' 
INTERSECT 
select customerid from sales where productName='X' 
INTERSTECT
select customerid from sales where productName='Z'

这是我能做的最好的吗？

Answer 1

不确定这是否适用于postgresql，但请尝试：

select customerid 
from sales 
where productName in ('X', 'Y', 'Z')
group by customerid
having count(distinct productName) = 3

Answer 2

您还可以从销售中选择3次：

select s1.customerID
from sales s1, sales s2, sales s3
where s1.productName = 'X'
    and S2.productName = 'Y'
    and S3.productName = 'Z'
    and (S1.customerID = S2.customerID
         and s2.customerID = s3.customerID);

或使用正确的连接语法重写（虽然可能不是100％......）

select s1.customerID
from sales s1
inner join sales S2
    on s1.customerId = S2.customerID
inner join sales S3
    on s2.customerID = S3.customerId
where s1.productName = 'X'
    and S2.productName = 'Y'
    and S3.productName = 'Z';

如何通过拥有相同的ID进行分组？

2 个答案: