Section 10 Oracle Quiz

Test: Quiz: Modeling Change: Time
1. How do you know when to use the different types of time in your design?

• The rules are fixed and should be followed
• It depends on the functional needs of the system (*)
• You would first determine the existence of the concept of time and map it against the Greenwich Mean Time
• Always model time, you can take it out later if it is not needed

2. Modeling historical data produces efficient ways for a business to operate such as:

• Modeling historical data does not help a business.
• Providing valuable information via reports to management . (*)
• Keeping track of holiday dates.
• Employees can work in two time zones.

3. When you add the concept of time to your data model, you are:

• Simplifying your model.
• Adding complexity to your model. (*)
• Just changing the model, but this does not change the complexity of it.
• None of the above.

4. Which of the following would be a logical constraint when modeling time for a country entity?

• People have births and deaths in their countries that must be tracked by the system.
• If you are doing a system for France or Germany, you would need security clearance.
• Countries may need an end date in your system, because they can change fundamentally over time, e.g. Yugoslavia. (*)
• You need a constant record of countries, because they are still countries, even if leadership changes over time, e.g. France, USA and most other countries.

5. If you are tracking employment dates for an employee, do you need to have an “End Date” attribute?

• Yes, because you always need an end date when you have a start date
• No, because an end date is usually redundant
• Yes, if the company wants to track employee information, like multiple start and end dates (*)
• No, not if the company likes the employee

6. What is the benefit to the users of a system that includes “time,” e.g. Start Date and End Date for Employees?

• Increased usability and flexibility of a system; we can the trace e.g. the different managers an employee had over time. (*)
• System becomes 100% unstable; allows users to log on and log off at will.
• Users are able to create complex programs in support of this component.
• Reporting becomes nearly impossible, users enjoy this.

7. It is desirable to have an entity called DAY with a holiday attribute when you want to track special holidays in a payroll system. True or False?

• True (*)
• False

Test: Quiz: Modeling Change: Price

1. You are doing a data model for a computer sales company, where the price goes down on a regular basis. If you want to allow them to modify the price and keep track of the changes, what is the best way to model this?

• A. Create a product entity and a related price entity with start and end dates, and then let the users enter the new price whenever required.
• B. Create a new item and a new price every day.
• C. Use a price entity with a start and end date
• D. Allow them to delete the item and enter a new one.
• E. Both A and C (*)

2. Why would you want to model a time component when designing a system that lets people buy bars of gold?

• The price of gold fluctuates and for determining price, you need to know the time of purchase (*)
• To allow the sales people to determine where the gold is coming from
• You would not want to model this, it is not important
• The Government of your country might want to be notified of this transaction.

3. Which of the following is a logical constraint that could result from considering how time impacts an example of data storage?

• End Date must be before the Start Date.
• ASSIGNMENT periods can overlap causing the database to crash.
• An ASSIGNMENT may only refer to a COUNTRY that is valid at the Start Date of the ASSIGNMENT. (*)
• Dates can be valued only with Time.

4. What is the function of logging or journaling in conceptual data models?

• Allows you to track the history of attribute values, relationships and/or entire entities (*)
• Gives a timestamp to all entities
• Represents entities as time in the data model
• Creates a fixed time for all events in a data model