如何连接两个表并获取数据

Question

我有两个 table，如下所示。

Table #1: 客户群 table:

No    Reg                     Name 
----------------------------------------
111   Account Owner           Josh
111   Customer Group          Josh Group

Table#2：客户table：

No    Name            Address
----------------------------------
111   Josh Ltd        Lala Land

我如何编写查询 returns 如下所示的数据：

No      Customer    Account_Owner  Customer_Group
--------------------------------------------------
111     Josh ltd    Josh           Josh Group

请协助

Answer 1

使用条件聚合：

select c.no, c.name as customer,
    max(case when cg.reg = 'Account Owner'  then name end) as account_owner,
    max(case when cg.reg = 'Customer Group' then name end) as customer_group
from customer c
inner join customer_group cg on cg.no = c.no
group by c.no, c.name