Add query optimization scripts and results

sql/cancel_order.sql

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+-- query optimization - task 3
+-- noqa: disable=CP03
+create procedure CancelOrder (in TargetOrderID int)
+begin
+delete from Orders
+where OrderID = TargetOrderID;
+
+select concat("Order ", TargetOrderID, if(row_count() = 1, " is cancelled", " doesn't exist")) as Confirmation;
+end

sql/get_max_quantity.sql

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+-- query optimization - task 1
+-- changes:
+--   interpreted quantity as the number of items in an order, because I assumed that Little lemon wants
+--   orders à la carte instead of fixed menus
+
+create procedure GetMaxQuantity () -- noqa: disable=CP03
+select count(OI.OrderItemID) as MaxQuantityInOrder
+from MenuItems as MI
+inner join OrderItems as OI on MI.MenuItemID = OI.MenuItemID
+group by OI.OrderID
+order by MaxQuantityInOrder desc
+limit 1

sql/get_order_detail.sql

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+-- query optimization - task 2
+-- changes:
+--   interpreted quantity as the number of items in an order, because I assumed that Little lemon wants
+--   orders à la carte instead of fixed menus
+
+prepare GetOrderDetail from "
+select
+    O.OrderID,
+    count(OI.MenuItemID) as Quantity,
+    O.BillAmount as Cost
+from Orders as O
+inner join OrderItems as OI on O.OrderID = OI.OrderID
+inner join Bookings as B on O.BookingID = B.BookingID
+where B.CustomerID = ?;
+";

sql/query_optimization_results.txt

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+# Task 1
+> delimiter $
+> source ./get_max_quantity.sql
+> delimiter ;
+> call GetMaxQuantity();
++--------------------+
+| MaxQuantityInOrder |
++--------------------+
+| 15                 |
++--------------------+
+
+# Task 2
+> source ./get_order_detail.sql
+> set @customerID = 1
+> execute GetOrderDetail using @customerID
++---------+----------+-------+
+| OrderID | Quantity | Cost  |
++---------+----------+-------+
+| 4       | 3        | 29.00 |
++---------+----------+-------+
+
+# Task 3
+> delimiter $
+> source ./cancel_order.sql
+> delimiter ;
+> call CancelOrder(2)
++----------------------+
+| Confirmation         |
++----------------------+
+| Order 2 is cancelled |
++----------------------+
+> select * from `Orders`
++---------+---------------------+---------------------+------------+-----------+
+| OrderID | Started             | Finished            | BillAmount | BookingID |
++---------+---------------------+---------------------+------------+-----------+
+| 1       | 2024-11-14 18:05:00 | 2023-10-01 19:25:00 | 82.50      | 1         |
+| 3       | 2024-11-14 19:10:00 | 2023-10-03 20:30:00 | 31.00      | 3         |
+| 4       | 2024-11-14 19:35:00 | 2023-10-04 20:50:00 | 29.00      | 4         |
+| 5       | 2024-11-14 19:40:00 | 2023-10-05 20:55:00 | 20.00      | 5         |
+| 6       | 2024-11-14 19:40:00 | 2023-10-06 20:45:00 | 150.50     | 6         |
++---------+---------------------+---------------------+------------+-----------+
+> call CancelOrder(2)
++-----------------------+
+| Confirmation          |
++-----------------------+
+| Order 2 doesn't exist |
++-----------------------+