mysql - 如何排除列出现在结果中？

Question

此查询返回季度销售额，但我想隐藏 order_date 列以免出现在结果中。 order_date 仅用于确定商品是否在该季度内购买。

SELECT item.item_id, item.item_name, item.item_type, item.item_price, SUM(orderdetail.order_quantity) AS 'Quantity Ordered', 
SUM(item.item_price*orderdetail.order_quantity) AS 'Total Sales Per Item', orders.order_date FROM item 
JOIN orderdetail ON item.item_id = orderdetail.item_id 
JOIN orders ON orderdetail.order_id = orders.order_id
GROUP BY item.item_id, item.item_name, item.item_price, item.item_type
HAVING order_date BETWEEN '2017-01-01' AND '2017-03-31'
ORDER BY item.item_id;

Answer 1

只需将其从select 列表中删除即可。这不会阻止您在 where 或 having 子句中使用它:

SELECT item.item_id, item.item_name, item.item_type, item.item_price, SUM(orderdetail.order_quantity) AS 'Quantity Ordered', 
SUM(item.item_price*orderdetail.order_quantity) AS 'Total Sales Per Item'
-- order_date removed here
FROM item 
JOIN orderdetail ON item.item_id = orderdetail.item_id 
JOIN orders ON orderdetail.order_id = orders.order_id
GROUP BY item.item_id, item.item_name, item.item_price, item.item_type
HAVING order_date BETWEEN '2017-01-01' AND '2017-03-31'
ORDER BY item.item_id;