Question

我正在尝试从Vendors表中将一个Column作为“VendorName”，并从Invoices表的InvoiceTotal列中将一列作为InvoiceAverage。我正在尝试对表格中每个供应商的发票总额进行平均

SELECT InvoiceTotal
FROM Invoices
GROUP BY Invoices.InvoiceTotal
ORDER BY AVG(InvoiceTotal)

就我所知，并没有给我任何我想要的东西

Answer 1

假设您加入了VendorId字段：

SELECT v.VendorName, AVG(i.InvoiceTotal) AS InvoiceAverage
FROM Invoices i
    JOIN Vendors v ON i.VendorId = v.VendorId
GROUP BY v.VendorName
ORDER BY AVG(i.InvoiceTotal)

Answer 2

select VendorName, avg(InvoiceTotal) as 'some column name'
from Invoices
group by VendorName
-- order by avg(InvoiceTotal) desc/ asc

您希望按平均值进行分组。这就是它的工作原理。

编写查询以显示来自两个不同表的数据

2 个答案: