假设您有一个名为"发票"的表,列"发票_id", "客户_id", "发票_日期"和"金额".写一个SQL查询,找到最高的平均发票金额的前5名客户,不包括任何购买次数低于10次的客户.
Here's a SQL query that should achieve the desired result:

```
SELECT 
    customer_id, 
    AVG(amount) AS average_invoice_amount, 
    COUNT(DISTINCT invoice_id) AS num_invoices
FROM invoices
GROUP BY customer_id
HAVING num_invoices >= 10
ORDER BY average_invoice_amount DESC
LIMIT 5;
```

This SQL query first groups all invoices by customer ID, calculates the average invoice amount and the number of invoices for each customer, and then filters out any customers who have made less than 10 purchases using the `HAVING` clause. Finally, the results are ordered in descending order based on the average invoice amount and limited to the top 5 results using the `LIMIT` clause.