Management Information Systems Chapter 5

Logical Data Elements
a. Character
b. Field or data item
c. Record
d. File or table
e. Database
Character
A single alphabetic, numeric, or other symbol
Field or data item
Represents an attribute (characteristic or quality) of some entity (object, person, place, event)
Examples: salary, job title
Record
Grouping of all the fields used to describe the attributes of an entity
Example: payroll record with name, SSN, pay rate
File or table
A group of related records
Database
An integrated collection of logically related data elements
Common database structures…
Hierarchical
Network
Relational
Object-oriented
Multi-dimensional
Hierarchical Structure
Early DBMS structure
Records arranged in tree-like structure
Relationships are one-to-many
Network Structure
Used in some mainframe DBMS packages
Many-to-many relationships
Relational Structure
Most widely used structure
Data elements are stored in tables
Row represents a record; column is a field
Can relate data in one file with data in another, if both files share a common data element
Relational Operations
**Select
Create a subset of records that meet a stated criterion Example: employees earning more than $30,000
**Join
Combine two or more tables temporarily
Looks like one big table
**Project
Create a subset of columns in a table
Multidimensional Structure
Variation of relational model
Uses multidimensional structures to organize data
Data elements are viewed as being in cubes
Popular for analytical databases that support Online Analytical Processing (OLAP)
Object-Oriented Structure
An object consists of
Data values describing the attributes of an entity
Operations that can be performed on the data
Encapsulation
Combine data and operations
Inheritance
New objects can be created by replicating some or all of the characteristics of parent objects
Object-Oriented Structure
Used in object-oriented database management systems (OODBMS)
Supports complex data types more efficiently than relational databases
Examples: graphic images, video clips, web pages
Evaluation of Database Structures
**Hierarchical
Works for structured, routine transactions
Can’t handle many-to-many relationship
**Network
More flexible than hierarchical
Unable to handle ad hoc requests
**Relational
Easily responds to ad hoc requests
Easier to work with and maintain
Not as efficient/quick as hierarchical or network
Database Development
Database Administrator (DBA)
In charge of enterprise database development
Improves the integrity and security of organizational databases
Uses Data Definition Language (DDL) to develop and specify data contents, relationships, and structure
Stores these specifications in a data dictionary or a metadata repository
Data Dictionary
A data dictionary
Contains data about data (metadata)
Relies on specialized software component to manage a database of data definitions
It contains information on..
The names and descriptions of all types of data records and their interrelationships
Requirements for end users’ access and use of application programs
Database maintenance
Security
Database Development steps
1. data planning
2. Requirements Specification
3. Conceptual Designs
4. Logical Design
5. Physical Design
1. data planning
Develops a model of Business processes

Develop an enterprise model that defines the basic business process of the enterprise

2. Requirements Specification
Defines information needs of end users in a business process

Description of users needs may be represented in natural language of using

3. Conceptual Design
4. Logical Design
5. Physical Design