使用 Python MySQLdb 执行多表查询

Question

我一直在尝试从两个不同的表中返回值，但似乎无法让 c.execute(query) 函数返回我想要的值。目前我的代码将返回第一个 c.fetchone()[0]，但第二个 fetchone()[5] 给出一个错误，它超出范围，这意味着它可能仍在尝试从我的“客户”表中获取数据它没有 6 列。我不认为我完全理解 MySQLdb 的工作原理，这很神奇，但找不到任何好的多表查询示例。这是我的代码 sn-p 下面！谢谢！

c, conn = connection()

            #check if already exists
            x = c.execute("SELECT * FROM clients WHERE email = (%s)", (thwart(email),))

            if int(x) > 0:
                flash("That email already has an account, please try a new email or sign in.")
                return render_template('register.html', form=form)
            else:
                c.execute("INSERT INTO clients (email, phone, password) VALUES (%s, %s, %s)", (thwart(email), thwart(phone), thwart(password)))
                c.execute("SELECT cid FROM clients WHERE email = (%s)", (thwart(email),))
                clientcid = c.fetchone()[0]
                c.execute("INSERT INTO cpersonals (first_name, last_name, address, zip) VALUES (%s, %s, %s, %s)", (thwart(first_name), thwart(last_name), thwart(address), czip))
                c.execute("SELECT reg_date FROM cpersonals WHERE cid = (%s)", (clientcid,))
                reg_date = c.fetchone()[5]
                rating = c.execute("SELECT rating FROM clients WHERE email = (%s)", (thwart(email),))
                conn.commit()
                flash("Thanks for registering!")
                c.close()
                conn.close()

Answer 1

您的查询是SELECT reg_date FROM cpersonals ...。您只选择一列。 fetchone()[5] 失败的原因是，获取的记录中没有第 6 列。尝试用0 代替5。

你为什么使用5？