Most operations in our POTR site are
related to the database, and are repeated. The Create, Retrieve, Update, and Delete
(CRUD) operations are most common. So let us create a common class that others
can extend??”the common class will have all database-related functions and other
frequently used methods.
Building Pizza On The Run
[ 52 ]
One order can contain multiple pizzas. Each pizza has a base price and the user can
customize the size, crust, and toppings, which add to the price. Thinking about all
this, we can have a class structure as shown in the following figure:
Database Schema
Deriving from the class structure, we can have a database schema as in the following
figure. A few important notes:
Product categories will be Pizzas, Side Dishes, and Beverages.
The Products table will contain details of individual products. Variations are
possible only on pizzas, so we don't need to relate them with all products.
The variation type will decide what type of variation it is??”Size, Crust,
or Toppings.
??? ??? ???
Chapter 3
[ 53 ]
Each order may have one or more products in it, and if the order item is a
pizza, it will have variations.
Pages:
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87