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.
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.
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.