DATABASE SYSTEM

DATABASE CONCEPTS

1. Data
A. Refers to raw facts.
B. Raw indicates that the facts are not yet been processed to reveal their meaning.
C. There are 2 kinds of data in DBMS:
1. Structured: text, numbers and dates
2. Unstructured: images, videos and documents
2. Information
 Is the result of processing raw data to reveal its meaning.
 To reveal the meaning, information requires context.
 Information can be used as the foundation for decision making.
 The key to a good decision making is its accuracy, relevance and timely information.
3. Data Management
 Is a discipline that focuses on the proper generation, storage, and retrieval of data.
 Efficient data management typically requires the use of a computer database.
4. Database
 Is a shared integrated computer structure that stores a collection of
a. End-user data that is, raw facts of interest to the end user.
b. Metadata, or data about data, through which the end-user data are integrated and
managed.
 Is a method of storing data on auxiliary storage so as to minimize the disadvantages that would be
present if using data files tied directly to particular programs.
5. Metadata
 Provides a description of the data characteristics and the set of relationships that link the data found
within the database.
 Metadata present a more complete picture of the data in the database.
6. Database Management System
 Is a collection of programs that manages the database structure and controls access to the data
stored in the database.
7. Field
 A character or group of characters (alphabetic or numeric) that has a specific meaning.
 A field is used to define and store data.
8. Record
 A logically connected set of one or more fields that describes a person, place or thing.
9. File
 A collection of related records.
 ADVANTAGES OF THE DBMS

Below are the different advantages of a DBMS

1. Improve data sharing

2. Improve data security
3. Better data integration
4. Minimize data inconsistency
5. Improved data access
6. Improved decision making
7. Increased end-user productivity

COSTS AND RISK OF THE DATABASE APPROACH

a. New, specialized personnel

b. Installation and management cost and complexity
c. Conversion costs
d. Need for explicit backup and recovery
e. Organizational conflict

RANGE OF DATABASE APPLICATIONS (CLASSIFICATIONS OF DATABASE)

1. Number of users
Determines whether the database is classified as single-user or multiuser.
A single user database that runs on a personal computer is called desktop database.
Workgroup database is a multiuser database that supports a relatively small number of users
(usually fewer than 50) or a specific department within an organization.
Enterprise database is a database used by the entire organization and supports many users (more
than 50, usually hundreds) across many departments.

2. Database location(s)
a. Centralized Database – database that supports data located at a single site.
b. Distributed Database – database that supports data distributed across several different sites.

3. Expected type and Extent of use

a. Operational/Transactional/Production database – database that is designed primarily to support
a company’s day-to-day operations.
b. XML (Extensible Markup Language) database – supports the storage and management of semi
structured XML data.
 COMPONENTS OF DATABASE ENVIRONMENT

1. Hardware

Refers to all of the system’s physical devices (ex. Computer, servers, workstations, router, hubs,
switches, fiber optics).

2. Software

To make the database system function fully, three types of software are needed:

a. Operating System Software – manages all the hardware components and makes it possible for all
other software to run on the computers.
b. DBMS Software – manages the database within the database system.
c. Application programs and utility software – used to access and manipulate data in the DBMS and
to manage the computer environment in which data access and manipulation take place.

3. People

a. System Administrator – oversees the database system’s general operations.

b. Data/Database Administrators – also known as DBA’s. Ensures database is functioning properly.
c. Database Designers – design the database structure. They are the database architect.
d. Systems Analyst and Programmers – design and implement the application programs.
e. End Users - people who use the application programs to run the organization’s daily operations.

4. Procedures

The instructions and rules that govern the design and use of the database system.
Enforce the standards by which business is conducted within the organization and with customers.
Used to ensure that there is an organized way to monitor and audit both the data that enter the
database and the information that is generated through the use of that data.

5. Data

Collection of facts stored in the database.

Repository - centralized storehouse of metadata
Database Management System (DBMS) - software for managing the database
Database - collection of logically related data.

DBMS FUNCTIONS

The function of a DBMS is vital to ensure integrity and consistency of data in the database. The functions of a
DBMS are as follows:

1. Data Dictionary management

2. Data storage management -
3. Data transformation and presentation
 4. Security management
5. Multiuser access control
6. Backup and recovery management
7. Data integrity management
8. Database access language and application programming interfaces
9. Database communication interfaces

DATABASE DEVELOPMENT PROCESS

Database development is a systematic process that moves from concept to design to implementation.

1. Define business processes - defining the key business and/or operational processes within the
organization.
2. Determine scope of database development effort - select one process or a set of related processes for
further analysis and improvement.
3. Define the information needs - define the information needs of users involved in or affected by the
business process.
4. Develop conceptual design - a conceptual data model is created that illustrates relationships between
information sources, users, and business process steps.
5. Develop logical data model - used to develop a logical data model based on one of the primary DBMS
types: relational, hierarchical, network, or object-oriented approaches.
6. Develop physical design - involves determining the specific storage and access methods and structures.
7. Create and test database - developers can go ahead and create the database using whatever DBMS has
been selected. Small amounts of data can be entered into the database for testing purposes. This is also
the time to start developing sample screens and reports to determine if the database design will meet the
predefined requirements.

The term prototyping refers to the iterative process used to try different report formats and input screens
to determine their suitability and effectiveness.

THREE SCHEMA ARCHITECHTURE

The objective of the schema is to separate each user’s view of the database from the way it is physically
presented. The schemas can be defined at the following three levels:

1. The external level or view level

 The external or view level includes a number of external schemas or user views.
 It describes the part of the database that a particular user group is interested in and hides the rest
of the database from that user group.
 Provides a powerful and flexible security mechanism by hiding parts of the DB from certain users.

2. The conceptual level

 What data is stored?
 It describes the entities, data types, relationships, user operations, and constraints.
 The relationships among the data.
3. The internal level
 The internal level has an internal schema which describes the physical storage structure of the
database.
 How the data is stored in the database.
4. Physical Model
 The physical model describes the way data are saved on storage media such as disk or tapes.
 Physical model is dependent on the DBMS, methods of accessing files, and types of hardware
storage devices supported by the operating system.

IMPORTANCE OF DATABASE DESIGN

 Database design refers to the activities that focus on the design of the database structure that will be used
to store and manage end-user data.
 A database design should identify precisely the database’s expected use.
 A well-designed database facilitates data management and generates accurate and valuable information.
 A good DBMS will perform poorly with a badly designed database.
 A proper database design requires the designer to identify precisely the database’s expected use.