| Lesson 5 | User views |
| Objective | Explain the role of requirements analysis in creating user views. |
The Role of Requirements Analysis in Creating User Views
Earlier lessons focused on designing normalized tables that support accurate, reliable data entry and maintenance.
Once stable tables are in place, the next challenge is transforming stored data into useful information.
The next modules introduce user views, virtual representations of data that present only what a user needs to see, and only in the format they require.
Requirements Analysis: Identifying Information Needs
The process of creating effective user views begins during the first phase of the Database Life Cycle:
Requirements Analysis[1].
In this phase, database designers interview business users to understand:
In this phase, database designers interview business users to understand:
- Which business objects the organization must track
- How these objects relate to one another
- What information each user role must obtain from the stored data
- Any restrictions on what particular users may view or modify
- Vehicles available for rent
- Special offers and their expiration dates
- Maintenance records
- Accident reports
- Details of each rental
- Customers
- Employees
Role-Based Access: Customer Service Representative Example
Requirements analysis does more than identify which objects belong in the database.
It also identifies which users need to access which subsets of data.
For example, a customer service representative needs access to:
Once these needs are documented, you construct views[2] to provide exactly the information required—no more and no less. Views act as a controlled, secure interface between the user and the underlying tables.
For example, a customer service representative needs access to:
- Vehicle availability
- Special offers
- Rental details
- Customer records
Once these needs are documented, you construct views[2] to provide exactly the information required—no more and no less. Views act as a controlled, secure interface between the user and the underlying tables.
Views and Calculated Information
Relational database design principles discourage storing calculated values in base tables.
Storing derived values violates Codd’s rule that each fact should appear in one place only.
Views solve this problem by allowing calculations in the view definition rather than in the base schema. Because a view is not a physical table, its calculated columns do not violate relational principles.
In a rental car agency, managers may rely on calculated fields such as:
Views solve this problem by allowing calculations in the view definition rather than in the base schema. Because a view is not a physical table, its calculated columns do not violate relational principles.
In a rental car agency, managers may rely on calculated fields such as:
- Percentage of vehicles available
- Maintenance frequency per model
- Percentage of drivers exceeding mileage limits
- Most popular models
- Total revenues
- Total labor cost
- Total maintenance cost
- Overall profit
User Views – Exercise
Before continuing to the next lesson, complete the following exercise to reinforce your understanding of requirements analysis and the role of user views.
User Views – Exercise
User Views – Exercise
[1]requirements analysis: The stage in the database design cycle in which designers learn what information the client needs to store, retrieve, and manage, and under what conditions that information must be accessed.
[2]view: A database object defining which columns and rows a user is permitted to see; views can also provide calculated fields and support security policies.