sql - oracle 中的 NULL & Distinct

Question

我有一种情况，我想从客户表中返回空值，并且本质上相当于在账单表中的账单代码上选择不同的值。

我该怎么做？

表客户

ID
姓名
客户编号
帐单代码

表账单

ID
帐单代码

我正在尝试做类似的事情

Select Null ID, Null NAME, Null CUSTNUMBER
from CUSTOMER
RIGHT JOIN ID, BILLCODE 
on customer.billcode = bill.billcode

我只想要表中每个账单代码的 1 条记录。

Answer 1

with billcodes as (select distinct billcode from bill)
select b.billcode, c.id, c.name, c.custnumber
from billcodes b
left outer join customer c on c.billcode=b.billcode

或者：

select b.billcode, c.id, c.name, c.custnumber
from (select distinct billcode from bill) b
left outer join customer c on c.billcode=b.billcode

Answer 2

I am guessing that the question is: how can I return all customers from the customer table with a list of each bill code they have?

If so, you want to use group by and left outer join:

select b.billcode, c.id, c.name, c.custnumber
from customer c left outer join
     bill b
     on c.billcode = b.billcode
group by b.billcode, c.id, c.name, c.custnumber