Question

通过类似的线索阅读，但我找不到为什么这不起作用的原因：

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;

不应该计算最大invoice_total的总和吗？继续给我“未知专栏”＃39;在最大值前添加总和时出错

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;

Answer 2

试试这个 - 给max（invoice_total）一个别名，然后在外部选择中使用它：

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

计算MySQL select语句的最大值之和

2 个答案: