按丢失或无效分组。 FoxPro 9

Question

我正在使用OLEDB访问FoxPro DBF文件，并在向SQL: GROUP BY clause is missing or invalid.命令添加另一个字段时不断出现SELECT错误。

这很好...

SELECT SUM(qty_shipd) AS total, item_no FROM arline 
WHERE invc_date >= {7/25/2018} AND invc_date <= {10/23/2018} 
GROUP BY item_no ORDER BY total DESC

当我尝试添加说明字段时，出现错误...

SELECT SUM(qty_shipd) AS total, item_no, print_desc FROM arline 
WHERE invc_date >= {7/25/2018} AND invc_date <= {10/23/2018} 
GROUP BY item_no, print_desc ORDER BY total DESC

为什么在添加其他字段时会出错？