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[英]Django query ORM to query based on primary key then get information from junction tables linked by foreign key
[英]I need to query information from two tables, using information connected through a foreign key?
這可能令人困惑,但基本上我擁有的是下表:
CREATE TABLE Employee( eid int NOT NULL, fname varchar(20), lname varchar(20), zip int, PRIMARY KEY (eid));
CREATE TABLE Customer( cid int NOT NULL, fname varchar(20), lname varchar(20), street varchar(20), city varchar(20), zip int, PRIMARY KEY (cid));
CREATE TABLE Orders( oid int NOT NULL, rdate date, sdate date, cid int NOT NULL, eid int NOT NULL, PRIMARY KEY (oid), FOREIGN KEY (cid) REFERENCES Customer(cid), FOREIGN KEY (eid) REFERENCES EMPLOYEE(eid));
我的作業的問題之一如下:
創建並執行一個查詢,列出員工信息以及他們處理的數量或訂單
有人可以幫助我開始嗎? 我真的不知道從哪里開始......
SELECT ??? FROM ??? WHERE ???
SELECT e.fname, e.lname, e.zip,
OrdersProcessed = COUNT(o.oid)
FROM Orders o
INNER JOIN Employee e ON o.eid = e.eid
GROUP BY e.fname, e.lname, e.zip
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