Ch.4 Part 1

Question 1

What is database?

Answer 1

Collection of organized data

Used by many different computer applications

Question 2

What is the ascending order of data organization?

Answer 2

Databases
File
Record
Dataefields

Question 3

What is a database?

Answer 3

Efficiently and centrally coordinates information for a related group of files

Question 4

What is the significance of a database?

Answer 4

Critical information
Volume
Distribution
Privacy
Irreplaceable data
Need for accuracy

Question 5

What is a database?

Answer 5

A database is a collection of related data for various uses.

Question 6

What are the three types of data models?

Answer 6

A Hierarchical data model organizes data into a tree-like structure that allows repeating information using defined parent/child relationships.
A Network data model is a flexible model representing objects and their relationships.
A Relational data model is a data model that stores information in the form of related two-dimensional tables.

Question 7

Additional information on network data models

Answer 7

Network data model allows each record to have multiple parent and child records.

Question 8

Additional Information on relational data model?

Answer 8

Relational data model allows designers and users to identify relationships at the time the database is created or much later whenever new informational requirements from the data model are desired.

Question 9

What is the difference between relational data model and the network and hierarchical models

Answer 9

While hierarchical and network data models require relationships to be formed at the database creation, relational data models can be made up as needed.

Question 10

What are the advantages of relational data models?

Answer 10

Flexibility and Scalability: handle changes quickly and easily (for example, S A P, Oracle, Microsoft, etc.).
Simplicity: easy to communicate to both database users and database developers.
Reduced Information Redundancy: requires each piece of data to be recorded only in one place.

Question 11

Advantages of Databases?

Answer 11

Data integration: An example is an employee database that consolidates data formerly contained in payroll, personnel, and job skills master files. This makes it easier for information to be combined in unlimited ways.
Data sharing: Integrating data makes it easier to share data with all authorized users.
Reporting flexibility: Reports can be revised easily and generated as needed and the database can be easily browsed to research a problem or obtain detailed information underlying a summary report.
Minimal data redundancy and data inconsistencies: Because data items are usually stored only once, data redundancy and data inconsistencies are minimized.
Central management of data: Data management is more efficient because a database administrator is responsible for coordinating, controlling, and managing the data across the organization.
Cross-functional analysis: In a database system, relationships can be explicitly defined and used in the preparation of management reports.
Data independence, this is a critical feature of the database approach, it is the separation of data from the program applications that access and process the data.(Data independence is achieved by interposing the database management system (DBMS) software between the database and the users of the data (e.g., the application programs)).

Question 12

What is database management systems(DBMS).

Answer 12

A database management system (DBMS) acts as an interface between the database and the various application programs.
A computer program that creates, modifies, and queries the database.
Designed to manage a database’s storage and retrieval of information.

Question 13

What is data dictionary?

Answer 13

Describes the data fields in each database record such as field description, field length, field type (for example, alphanumeric, numeric), etc.

Question 14

What is database Adminstrator?

Answer 14

The person responsible for the design, implementation, repair and security of a firm’s database.

Question 15

Examples of Entities and Attributes

Answer 15

Entities(classes). A class in the relational databases model could be a person, place, thing, transaction, or event which information is stored.

• Resources
• Events
• Agents

Attributes.(Attributes are characteristics, proprieties, or adjectives that describes each class)

• Characteristics
• Properties
• Adjectives

Question 16

What is primary key?(keys and relationships)

Answer 16

Uniquely identifies a specific row in a table

Question 17

What is foreign key?(Keys and Relationships)

Answer 17

Attribute in one table that acts as primary key in another table.
Provides a logical relationship, or a link, between two tables.

Question 18

What are the basic requirements of tables

Answer 18

The Entity Integrity Rule: the primary key must have data values (cannot be null).
The Referential Integrity Rule: the data value for a foreign key must either be null or match one of the data values that already exists in the corresponding table.
Each attribute: unique name.
Value of each attribute: same type.
Each attribute (column) of a record (row): single-valued.
All other non key attributes: describe a characteristic of the class (table) identified by the primary key.

Question 19

What is file?

Answer 19

releated group of records

Question 20

What is record?

Answer 20

related group of fields

Question 21

What is a field

Answer 21

specific attribute of interest for the entity?