如何连接两个表并获取数据

Question

我有两张表，如下所示。

表#1：客户组表：

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

表 #2：客户表：

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

如何编写一个返回如下所示数据的查询：

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

请帮忙

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