完成大作业服务端代码，新建管理端，管理端不可用

Project/Service/func/cancel_order.py

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+from flask import request, redirect, url_for, g
+from .config import db
+import pymysql
+
+def cancel_order():
+    order_id = request.args.get('order_id')
+    if not g.user:
+        return redirect(url_for("login"))
+    conn = pymysql.connect(**db)
+    cursor = conn.cursor(pymysql.cursors.DictCursor)
+
+    # 检查订单是否存在
+    check_order_sql = "SELECT ID FROM Orders WHERE ID = %s"
+    cursor.execute(check_order_sql, (order_id,))
+    order_exists = cursor.fetchone()
+
+    if not order_exists:
+        cursor.close()
+        conn.close()
+        return redirect(url_for("order_list"))
+
+    # 查询订单中所有机票的航班ID和座位级别
+    tickets_sql = "SELECT FlightID, Seat_class FROM Tickets WHERE OrderID = %s"
+    cursor.execute(tickets_sql, (order_id,))
+    tickets = cursor.fetchall()
+
+    # 恢复航班的对应余座数
+    for ticket in tickets:
+        flight_id = ticket['FlightID']
+        seat_class = ticket['Seat_class']
+        seat_column = seat_class.replace(' ', '_').lower() + "_seats_remaining"
+        update_seat_sql = f"""
+        UPDATE Flights
+        SET {seat_column} = {seat_column} + 1
+        WHERE ID = %s
+        """
+        cursor.execute(update_seat_sql, (flight_id,))
+
+    # 删除对应的机票
+    delete_tickets_sql = "DELETE FROM Tickets WHERE OrderID = %s"
+    cursor.execute(delete_tickets_sql, (order_id,))
+
+    # 删除订单
+    delete_order_sql = "DELETE FROM Orders WHERE ID = %s"
+    cursor.execute(delete_order_sql, (order_id,))
+
+    conn.commit()
+    cursor.close()
+    conn.close()
+
+    return redirect(url_for('order_list'))