Data Modeling

Assignment 1

Questions

1. What is a database?

A database is a collection of information organized in a way that a computer program can quickly select data. You can think of a database as an electronic filing system. Traditional databases are organized by fields, records, and files.

Give an example of a database you may have used.

Personal address books, telephone books, card catalogs at libraries, online stores, finance software, road maps.

2. Discuss each of the following terms.

  • Data - Facts and statistics collected together for reference or analysis.
  • Column (fields) - a set of data values of a particular simple type, one for each row of the table.
  • Record (row or tuple) - represents a single implicitly structured data item in a table.
  • DMBS - Database Management System

3. What is the difference between OLTP and OLAP?

  • OLTP (Online Transactional Processing)- is a class of information systems that manage transaction-oriented applications, typically for data entry and retrieval and processing of transactions.
  • OLAP (Online Analytical Processing)- is characterized by relatively low volume of transactions. Queries are often very complex and involve aggregations.

4. Explain how a business could benefit by implementing a database? Give an example.

Databases store information in electronic records that may be searched, retrieved and organized in countless ways. Having your information in a database, instead of on paper or in spreadsheets, not only saves you time and preserves vital information, it allows you to see patterns in your operations that are visible in no other way.

Example:
Keeping track of multiple Projects, the employees on the projects, the cost, and the pay of that set project.

5. Before a database is implemented for a company, what should be done first?

Extreme vetting should be done before implementing a database to a company, to make sure everything will be accessible and function well with the structure of the company.

6. What are business rules and why are they important?

Businesses have rules that affect how business operates, business rules tells us how data is Create, modify and deleted when designing a database. Business rules are important to the structure of the database and how the database is designed and accessed.

7. What is the difference between data and information?

  • Data is raw, unorganized facts that need to be processed. When data is processed, organized, structured or presented in a given context as to make it useful, it is called information.

Problems

1. How many records does the table contain and how many fields are there per record?

There are 7 records and 5 fields per record in the table

2. What problems would you encounter if you wanted to produce a listing by city? How would you solve this problem by altering the structure above?

You couldn’t search by city, as they are listed by full address. The data for the address should be listed as its own entity with its own attributes to be able to easily retrieve the information.

3. If you wanted to produce a listing of the table contents by last name, area code, city, state, or zip code, how would you alter the table structure above?

Make a new table to create a new table to separate employee information from project information

4. What data redundancies do you detect, and how could these redundancies lead to anomalies?

Employees should be organized with an employee number in order to reduce redundancies within the table and no confusion is created.

5. Using two relational database tables, PROJECT and MANAGER, eliminate the redundancies discovered in problem 4. Connect the two tables through an appropriate link

relational database 5

6. Given the table structure shown in the figure below, what problem(s) might you encounter if you deleted building KOM.

You would lose the records of the names, room codes and initials for those specific teachers.

7. Describe (write out) the relationship depicted in the ERD shown below

Professor teachers many classes. Many classes are taught by 1 professor. 1 professor advises many students. Many students are advised by 1 professor.

8. Convert the ERD in problem 7 into a crow’s foot model.

Problem8

9. Create a Crow’s Foot ERD for each of the following descriptions. (Note: The word “many” merely means “more than one” in the database-modeling environment. Describe the relationship shown in the ERD below

1 employee writes many invoices. Many invoices are written by 1 employee. A customer pays many invoices. Many invoices are paid by 1 customer.

10. Create a Crow’s Foot ERD for each of the following descriptions. (Note: The word “many” merely means “more than one” in the database-modeling environment.

Each of the Mega Co Corporation’s division is composed of many departments. Each of those departments has many employees assigned to it, but each employee works for only one department. One employee manages each department, and each of those managers can manage only one department at a time.

Problem10-1

During some period of time, a customer can rent many videotapes from BigVid store. Each of the BigVid’s videotapes can be rented to many customers during that period of time

Problem10-2

An airliner can be assigned to fly many flights, but each flight is flown by only one airliner.

Problem10-3

The KwikTite Corporation operates many factories. Each factory is located in a region. Each region can be “home” to many of KwikTite’s factories. Each factory employs many employees, but each of those employees is employed by only one factory.

Problem10-4