MySQL - 變換簡單表格

Question

這似乎很容易，但我有一種感覺，它可能需要很多步驟來實現。有沒有簡單的方法來做到這一點？

Answer 1

您正在尋找的聚集功能，特別是group_concat()。關鍵是你想做兩個聚合：

select subgroupcombo, count(*) as NumCustomers, sum(spend) as TotalSpend, 
     sum(Transactions) as TotalTransactions 
from (select customer, group_concat(subgroup order by subgroup) as subgroupcombo, 
      sum(spend) as spend, sum(transactions) as transactions 
     from input i 
     group by customer 
    ) c 
group by subgroupcombo;