对具有一对多关系的3个表的SQL查询

Question

我需要帮助找出我的电子商务网站的SQL查询

有Users（客户/客户服务代表）表

有Orders表

有Line-Items（列是制造商，数量，等）表

用户有许多订单，订单有很多订单项。

我正在尝试查找已生成1个或更多订单的用户列表，其中包含来自（'X-Parts'< - 制造商名称）的项目

任何帮助将不胜感激

Answer 1

试试这个

SELECT U.UserID, COUNT(O.OrderID) OrderCount
FROM Users U INNER JOIN Orders O ON U.UserID = O.UserID
             INNER JOIN Line-Items L ON O.OrderID = L.OrderID
Where L.manufacturer = 'X-Parts'
Group BY U.UserID
Having count(O.orderID) >= 1

示例演示： - http://sqlfiddle.com/#!3/f1712/2

Answer 2

Its one or more orders.

SELECT U.UserID, COUNT(O.OrderID) as OrderCount
FROM Users U 
INNER JOIN Orders O ON U.UserID = O.UserID
INNER JOIN Line-Items L ON O.OrderID = L.OrderID
Where L.manufacturer = 'X-Parts'
Group BY U.UserID
Having count(O.orderID) >= 1