查找购买了相同数量商品的一对客户（CustID）。（SQL嵌套查询）

Question

• 发票（发票编号，客户编号，出口编号，日期）PK（发票编号）
• InvoiceItems（发票编号，ItemID，数量，折扣）PK（InvoiceNO，ItemID）

PLz告诉我上述两个表结构的嵌套方法查询的解决方案。 我无法解决。

Answer 1

这应该可以解决问题。

Select i1.CustID, i2.CustID
From
    (Select InvoiceNo,count(*) as nb
         From InvoiceItems
         Group by InvoiceNo) as a,
    (Select InvoiceNo,count(*) as nb
         From InvoiceItems
         Group by InvoiceNo) as b,
    Invoice as i1,
    Invoice as i2
Where a.InvoiceNo = i1.InvoiceNo
    and b.InvoiceNo = i2.InvoiceNo
    and a.InvoiceNo < b.InvoiceNo
    and a.nb = b.nb;