mysql - 计算 MySQL select 语句的最大值之和

Question

阅读类似的线程，但我找不到这不起作用的原因:

select sum(max(i.invoice_total)) as 'Sum of Largest Unpaid Invoice'
from (select vendor_id, MAX(invoice_total)
from vendors v join invoices i using (vendor_id)
where i.payment_date is null
group by v.vendor_id) as alias;

这不是应该计算最大invoice_total的总和吗？当我在最大值前面添加总和时，不断出现“未知列”错误。

Answer 1

您需要为该列命名。 。 。我会明确地这样做:

select sum(max_invoice_total) as `Sum of Largest Unpaid Invoice`
from (select vendor_id, MAX(invoice_total) as max_invoice_total
      from vendors v join
           invoices i
           using (vendor_id)
      where i.payment_date is null
      group by v.vendor_id
     ) alias;