sql总和特定计数值

Question

I am trying to make a sql script that count the number of customers grouped by branch and it worked, but I want to divide the counted branches into region and sum every region, like this:

  numberofcustomer |  branch
-------------------+-----
                 3 | branch1-1
                 4 | branch1-2
                 7 | region1
                 3 | branch2-1
                 3 | branch2-2
                 2 | branch2-3
                 5 | region2

here is my code:

select Branch_name,
COUNT(customer.customerID) as numberofcustomer 
from customer inner join Branch
on customer.BranchID = Branch.BranchID 
group by Branch_name
ORDER By Branch_name

here is the result of my code:

  numberofcustomer | branch
-------------------+-----
                 3 | branch1-1
                 4 | branch1-2
                 3 | branch2-1
                 3 | branch2-2
                 2 | branch2-3

Answer 1

为什么不为区域创建另一个表，为区域创建表，在分支表中已经添加了区域ID作为fk，例如，在两个表之间建立内部联接，例如在查询中，在两个表之间进行内部联接A和客户以及按地区名称分组