Module 1: Generate a logical data model Build a logical data model to illustrate the reservation system of the hotel. This data model will be one subject area of the overall system. The entity relation diagram is a logical representation of the data structure and data relationships of the database. It focuses on what is represented in the database (how it is represented is covered in the physical diagram). It includes entities to represent each person, place, event, or concept about which information will be maintained in the system, and relation lines to represent the associations between the entities. Logical Data Model From the conceptual model, you can develop a logical model, by adding details. For example, you replace the Non-specific relation line between entities with Identifying or Non-Identifying relationships. You model the attributes of the entities, and specify their generic data types. You can normalize your model, and specify which attributes are primary and foreign keys for the entities. You might even specify access paths for the entities–ways in which entities can be navigated to find information quickly. (Access paths are the logical counterpart to indexes and constraints in a physical diagram.) Learning objectives After completing the lessons in this module you will know how to: ▪ create a subject area diagram ▪ draw and define entities and their components ▪ draw and define relation lines ▪ propagate foreign key roles and enter role names ▪ create a second subject area diagram ▪ create and manage a model diagram Time required This module should take approximately 60 minutes to complete. Prerequisites To complete this module, you will need to have the Tutorial encyclopedia open. If you need directions on how to open prebuilt encyclopedias, or this encyclopedia is not attached to your server, refer to the Introduction section of this module. Lessons in this module Lesson 1.1: Create a subject area diagram Create a subject area diagram for a small section in the hotel system. Lesson 1.2: Draw and define entities and their components Draw entities to represent a hotel guest, reservation, room, and vehicle. Define these entities by adding the attributes name and guest number. Lesson 1.3: Draw and define relation lines Draw relation lines to identify what an entity does. Draw relation lines between a hotel guest, reservation, vehicle, and room. Define their relationship to each other. Lesson 1.4: Propagate foreign key roles and enter role names Propagate foreign key roles from the parent entity to the child entity using the hotel dictionary. Enter roles to differentiate from an attribute with the same name. Lesson 1.5: Create a second subject area diagram Create another subject area to connect entities to and from other entities. Lesson 1.6: Create and manage a model diagram Create a model diagram of for the Hotel Reservation System and understand how to delete objects in the model diagram. Next Lesson 1.1: Create a subject area diagram See also Introduction: Relational data modeling for data architecture Relational data modeling for data architecture