Question

我的表格PURCHASES包含以下列：NAME，ORDER_ID，ITEM_ID。

当客户订购2件商品时，会在相同的ORDER_ID下记录2行，并且两个相同或不同的ITEM_ID（取决于客户是否购买了相同的商品）。

我想选择总共少于3个订单且少于4个订单的所有客户（无论它们是否相同）。这是当前的代码：

SELECT NAME, COUNT(DISTINCT ORDER_ID) AS number_of_orders, COUNT(ITEM_ID) AS number_of_items
FROM `PURCHASES`
WHERE number_of_orders <3
AND number_of_items <4
GROUP BY NAME
ORDER BY number_of_items DESC

我收到以下错误消息：Unknown column 'number_of_orders' in 'where clause'

Answer 1

您应该使用子查询

SELECT * FROM (
  SELECT NAME, COUNT(DISTINCT ORDER_ID) AS number_of_orders, COUNT(ITEM_ID)   AS number_of_items)
FROM `PURCHASES`
WHERE number_of_orders <3
    AND number_of_items <4
GROUP BY NAME
ORDER BY number_of_items DESC

Answer 2

使用此查询

SELECT NAME, COUNT(DISTINCT ORDER_ID) AS number_of_orders, COUNT(ITEM_ID) AS
number_of_items
FROM `PURCHASES`
GROUP BY NAME
HAving COUNT(DISTINCT ORDER_ID) <3
AND COUNT(ITEM_ID) <4
ORDER BY number_of_items DESC

根据许多订单选择行

2 个答案: