计算MySQL select语句的最大值之和

阅读类似的文章，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;

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这不应该计算最大发票总额吗？当我将总和添加到最大值之前时，一直给我“未知列”错误。

您需要命名列。我要明确地这样做：

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;

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您需要为列命名。我要明确地这样做：

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;

尝试此操作-为max（invoice_total）指定一个别名，然后在外部选择中使用该别名：

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;

尝试此操作-为max（invoice_total）指定一个别名，然后在外部选择中使用该别名：

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;

您需要在内部查询中为Max（发票总额）别名。不能有类似于（sum（Max（变量））的行。您需要在内部查询中为Max（发票总额）别名。不能有类似于（sum（Max（变量））的行