Field
Group of words or a complete number
Database
Group of related files
File
Group of records of same type
Entity
Person, place, thing, event about which information is maintained
Attribute
Description of a particular entity
Key field
A unique identifier field used to retrieve, update, sort a record
Problems with Traditional Data Management
- Data Duplication
- Program Data Dependence
- Lack of Flexibility
- Poor Security
- Data Sharing Difficulties
Data Duplication
is the presence of duplicate data in multiple data files so that the same data are stored in more than one place or location.
Program-Data Dependence
Program-data dependence refers to the coupling of data stored in files and the specific programs required to update and maintain those files such that changes in programs require changes to the data
Lack of flexibility
A traditional file system can deliver routine scheduled reports after extensive programming efforts, but it cannot deliver ad hoc reports or respond to unanticipated information requirements in a timely fashion.
Poor security
Because there is little control or management of data, access to and dissemination of information may be out of control.
* Management may have no way of knowing who is accessing or even making changes to the organization’s data.
Problems with Traditional Data Management
The lack of control over access to data in this confused environment does not make it easy for people to obtain information.
* Because pieces of information in different files and different parts of the organization cannot be related to one another, it is virtually impossible for information to be shared or accessed in a timely manner
Modern Data Base Management Systems
-Creates and maintain databases
-Eliminates requirement for data definition statements
-Acts as interface between application programs and physical data files
-Separates logical (conceptual) and physical views of data
Modern Data Base Management Systems-Data Definition, Manipulation and Dictionary
Data Definition Language : Specifies content and structure of database and defines each data element
Data Manipulation Language : Manipulates data in a database Data Dictionary : Stores definitions of data elements, and data characteristic
Types of Data Base Management Systems
Relational DBMS
Hierarchical and Network DBMS Object Oriented Databases
Relational Database Management Systems
-Represents data as two tables called relations dimensional
Relates data across tables based on common data element
Examples: DB2, Oracle, MS SQL Server
Relational Database Management Systems-Select, Join and Project
Select : Creates subset of rows that meet specific criteria
Join : Combines relational tables to provide users with information
Project : Enables users to create new tables containing only relevant information
Object Based DBMS
- Object-oriented DBMS: Allows for storage of multimedia objects as well as alphanumeric characters.
- Object-Relational DBMS: Provides capabilities of both object-oriented and relational DBMS
Structured Query Language
The Structured Query Language is the most popular data manipulation language,
- Basic SQL Commands– SELECT: Specifies columns– FROM: Identifies tables or views–
WHERE: Specifies conditions
Designing a Database
- Logical (Conceptual) Design: Abstract model of database from a business perspective
- Physical Design: Detailed description of business information needs
Designing A Database Conceptual Design
- Entity-Relationship Diagram: Methodology for documenting databases illustrating relationships between database entities
- Normalization: Process of creating small stable data structures from complex groups of data
Database Trends
On-line analytical processing (OLAP)
- Multidimensional data analysis * Supports manipulation and analysis of large volumes of data from multiple dimensions/perspectives
Database Trends
Data warehouse
- Supports reporting and query tools
- Stores current and historical data
- Consolidates data for management analysis and decision making
Database Trends
Data mart
- Subset of data warehouse
- Contains summarized or highly focused portion of data for a specified function or group of users
