MS-Access SQL语法错误中的子查询

Question

晚安。

我正在尝试创建一个平均每个产品购买量的查询。购买平均金额的购买次数。

这包括三个表：

1. CUSTOMER
2. 发票
3. LINE

我写了这个：

SELECT CUSTOMER.CUS_CODE, CUS_FNAME+" "+CUS_LNAME AS Name, CUSTOMER.CUS_BALANCE,    
Sum([LINE]![LINE_NUMBER]*[LINE]![LINE_PRICE]) AS Total_purchases,  
Count(INVOICE.INV_NUMBER) AS Number_of_purchases, 

(
SELECT [Sum([LINE]![LINE_NUMBER]*[LINE]![LINE_PRICE]) /   
[Count(INVOICE.INV_NUMBER)]
FROM INVOICE, LINE
WHERE INVOICE.INV_NUMBER = LINE.INV_NUMBER
) AS Average_purchase_amount

FROM CUSTOMER, INVOICE, LINE
WHERE CUSTOMER.CUS_CODE = INVOICE.CUS_CODE AND INVOICE.INV_NUMBER = LINE.INV_NUMBER 
GROUP BY CUSTOMER.CUS_CODE, CUS_FNAME+" "+CUS_LNAME, CUSTOMER.CUS_BALANCE;

---

我在第二个SELECT时遇到错误。我不知道为什么。我觉得我错过了很简单的事情。

实际错误为：

• “查询表达式中的语法错误”（  SELECT [Sum（[LINE]！[LINE_NUMBER] * [LINE]！[LINE_PRICE]）/ [Count（INVOICE.INV_NUMBER）]。'“

从错误中我认为在我的表达中的某些地方没有排队，但我想我不知道究竟发生了什么事情。

Answer 1

有不平衡的括号。要么每个都在括号或整个等式中：

SELECT [Sum([LINE]![LINE_NUMBER]*[LINE]![LINE_PRICE])] / [Count(INVOICE.INV_NUMBER)]

- 或 -

SELECT [Sum([LINE]![LINE_NUMBER]*[LINE]![LINE_PRICE]) /  Count(INVOICE.INV_NUMBER)]

尝试加入你的表格。像这样：

FROM INVOICE
    INNER JOIN CUSTOMER ON CUSTOMER.CUS_CODE = INVOICE.CUS_CODE
    INNER JOIN LINE ON LINE.INV_NUMBER =INVOICE.INV_NUMBER