Module 9
Review Questions 1-10
1. Explain the main difference between a file-oriented system and a database system.
a. A file-oriented system utilizes data in a regular OS file based format where a database system uses a database engine that organizes data in a database in a table format utilizing rows for each record.

2. What is a DBMS? Briefly describe the components of a DBMS.
a. DBMS stands for Database Management System. A DBMS is a collection of tools, features, and interfaces that enables users to add, update, manage, access, and analyze the contents of a database. A DBMS is made up of a DML (data manipulation language), Schema and subschemas, Physical data repository, and an Interface to allow access to the database from DBA’s, Users, and Related Information Systems.

3. Describe a primary key, candidate key, secondary key, foreign key, and common field.
a. Primary Key – a field or combination of fields that uniquely and minimally identifies an entity.
Candidate Key – Any field or combination of fields that can act as the primary key but are not.
Secondary Key – Any field of combination of fields that can be use to identify a entity.
Foreign Key – A field that exists in an entity that is the PK of another entity.
Common Field – An attribute (field) that appears in more than one entity (record).

4. What are entity-relationship diagrams and how are they used? What symbol is used to represent and entity in an ERD? What symbol is used for a relationship? What is cardinality, and what symbols do you use in the crow’s foot notation method?
a. An ERD graphically displays the relationship between two or more entities.

The symbol used to represent an entity is a rectangle and the relationship symbol is a diamond.

Cardinality describes the relationship between entities.

Crow’s foot notation is used to show Cardinality between