我该如何编写查询来查找到期余额高于所有未付发票的平均余额？

Question

编写一个查询，该查询返回具有InvoiceDate的发票  2016年4月1日之前，且余额应高于  所有未付发票的平均余额。的  查询结果应显示InvoiceNumber，InvoiceDate，  每个此类发票的发票总额和余额。分类  查询结果按Balancedue降序排列。 （注意：应付余额= InvoiceTotal – PaymentTotal -CreditTotal 未付发票是余额为<> 0）* /

的发票

        PaymentTotal 
        - CreditTotal AS BalanceDue
        FROM Invoices
        WHERE InvoiceDate < 2016-04-01 AND InvoiceTotal - PaymentTotal 
       - CreditTotal > 
                    (SELECT InvoiceTotal - PaymentTotal 
                    - CreditTotal AS BalanceDue
                    FROM Invoices
                    HAVING AVG(InvoiceTotal - PaymentTotal 
                    - CreditTotal) <> 0)

我已经尝试了上述方法，但似乎无法正确解决问题。