Mid-Term Exam Review

Question 1

Define data and information. How are they different?

Answer 1

• Data consists of raw facts
  − Not yet processed to reveal meaning to the end user
  − Building blocks of information
• Information results from processing raw data to reveal meaning
  − Requires context
  − Bedrock of knowledge
  − Should be accurate, relevant, and timely

Question 2

What is the role of the DBMS in processing data into information?

Answer 2

It offers a centralized and organized environment for data storage, retrieval, manipulation, and analysis.

Question 3

What are the major benefits of SQL? What does it mean that SQL is a non-procedural language?

Answer 3

*Benefits
- Data Retrieval and Manipulation, Data Security and Integrity, Data Analysis and Reporting, Versatility and Flexibility

*Non-procedural language
-The task that has to be done can be described by the user to the SQL and the SQL compiler will generate a procedure for the navigation in the database for the desired task automatically.

Question 4

Databases can be classified into different types, by their size, their location, the types of data stored, and how they are used. Define and describe each type, giving examples of each.

Answer 4

• Single-user database: supports one user at a time
• Multiuser database: supports multiple users at the same time
• General-purpose database: contains a wide variety of data used in multiple
  disciplines
  − Discipline-specific database: contains data focused on specific subject areas
  − Operational database: designed to support a company’s day-to-day
  operations
• Analytical database: stores historical data and business metrics used
  exclusively for tactical or strategic decision making

Question 5

What are the advantages and disadvantages of centralized and decentralized databases?

Answer 5

*Centralized
-Advantages: Simplified Administration and Management, Data Integration and Analysis, Performance and Scalability
-Disadvantages: Limited Autonomy and Flexibility, Single Point of Failure, Potential for Data Silos

*Decentralized
-Advantages: Potential for Data Silos, Increased Autonomy and Flexibility, Reduced Risk of Data Silos
-Disadvantages: Complex, Potential for Performance Issues, Data Integration and Analysis Challenges

Question 6

What is the traditional file system?

Answer 6

A method of storing and organizing data in individual files on a computer. It utilizes a hierarchical structure, where files are stored in folders and subfolders, similar to a physical filing cabinet.

Question 7

What is a conceptual model?

Answer 7

The output of the conceptual design process. The conceptual model provides a global view of an entire database and describes the main data objects, avoiding details.

Question 8

What is a data model?

Answer 8

A representation, usually graphic, of a complex “real-world” data structure. Data models are used in the database design phase of the Database Life Cycle.

Question 9

Why do we need conceptual and data models?

Answer 9

Conceptual data model = Provides a data-centric perspective of the organization by documenting how different business entities relate to one another.

Data model = Provides a bird’s-eye (macro level) view of the data environment that is relatively easy to understand.

Question 10

What is a business rule, and how is it derived?

Answer 10

Business rules set the stage for the proper identification of entities, attributes, relationships, and constraints
− Nouns translate into entities
− Verbs translate into relationships among entities

Question 11

What are the basic building blocks of a data model?

Answer 11

Entities, Attributes, Relationships, and Constraints

Question 12

Define and give an example of entities, attributes, relationships, and constraints.

Answer 12

Entity: person, place, thing, or event about which data will be collected and stored
− Attribute: characteristic of an entity
− Relationship: association among entities
 One-to-many (1:M OR 1..*)
 Many-to-many (M:N or ..)
 One-to-one (1:1 OR 1..1)
− Constraint: restriction placed on data
 Ensures data integrity

Question 13

In an ERD, how are entities, attributes, relationships, and constraints drawn?

Answer 13

A defined set of symbols such as rectangles, diamonds, ovals and connecting lines to depict the interconnectedness of entities, relationships and their attributes.

Question 14

What is a null? What impacts does a null have, and is there a way to limit these impacts?

Answer 14

Definition: The absence of any data value.
* Impacts: Data Inconsistency and Inaccuracies, Difficulty in Data Analysis and Manipulation
* How to limit impacts: Using default values and following normalization principles