SQL Server 2012将两个表中的列合并为一个

Question

我在不同地方有两张桌子

最终结果必须是

VendorName  InvoiceNumber  InvoiceTotal

VendorName在名为Vendors的表中

InvoiceNumber和InvoiceTotal在名为Invoices的表中

即使供应商没有任何发票，它也需要显示结果中的所有供应商，最大的发票总数首先显示DESC，并按字母顺序对供应商名称进行排序。

我试图将发票加入我的账户

SELECT VendorName FROM Vendors 

但我不知道语法：/

Answer 1

使用LEFT JOIN来包括那些没有发票的供应商，例如：

SELECT 
  v.VendorName, i.InvoiceNumber, i.InvoiceTotal
FROM Vendors v
LEFT JOIN Invoices i ON v.Id = i.VendorID
ORDER BY i.InvoiceTotal DESC, v.VendorName ASC

Answer 2

您将需要使用LEFT JOIN来LEFT JOIN与两个表相关的列上的两个表。 使用LEFT JOIN将返回所有vendors即使他们在invoices表中没有条目：

select v.vendorname,
    i.invoicenumber,
    i.invoicetotal
from vendors v
left join invoices i
    on v.vendorid = i.vendorid  -- this is the column relating the two tables
order by i.invoicetotal DESC, v.vendorname ASC

如果您在学习JOIN语法方面需要帮助，这是对联接的直观说明

Answer 3

您需要一个外部OUTER JOIN 。 假设PK / FK是VendorID ：

SELECT v.VendorName, i.InvoiceNumber, i.InvoiceTotal
FROM Vendors v
LEFT OUTER JOIN Invoices i ON v.VendorID = i.VendorID
ORDER BY v.VendorName   ASC
      ,  i.InvoiceTotal DESC

Answer 4

尝试：

SELECT Vendors.VendorName, Invoices.InvoiceNumber, Invoices.InvoiceTotal 
FROM Vendors LEFT JOIN Vendors.VendorID on Invoices.VendorId 
ORDER BY Invoices.InvoiceTotal DESC

您是要将通风器归为一组，还是供应商出现在结果集中多于1次？ 例如，您可以使用SUM（Invoices.InvoiceTotal）来获取InvoiceTotals的总数。

Answer 5

您的意思是：

select VendorName
      ,Count(InvoiceAmount) As InvoiceNumber
      ,Sum(InvoiceAmount) As InvoiceTotal
  from Vendor
  left join Invoices on Vendor.VendorId = Invoices.VendorId
 group by VendorName
 order by 3 Desc