Database Definitions and Concepts

Data and Information

What is Data?

Data is a raw fact or value. It represents facts about anything (objects, things, people, entities, events, etc.) and can be in any form such as image, file, voice recording, video, or plain text.

Importance of Data

Data is the foundation for decision-making in the world and is a precious resource for businesses and individuals.

Examples of Data Needs

  • Cost

  • PC Specification

  • Supportive device

Example: When buying a PC desktop, data is needed to decide which model to purchase.

What is Information?

Information is data that has been processed and organized into a form suitable for making decisions.

Data vs. Information Example

  • Data: 070707-07-5007

  • Information: year of birth, month of birth, date of birth, age, gender, state of birth

What is a Database?

A database is a shared collection of logically related data and a description of this data, designed to meet the information needs of an organization. It offers a flexible, reliable, and secure way to organize data.

A database can be considered a container filled with data or information which is electronically stored in a computer system.

Why Use a Database?

Databases provide ease of access, modification, protection, and analysis. For example, a student's database allows for easy access, modification, protection and analysis of their name, registration number, program, and results.

Uses and Importance of Databases in Business

  • Storing data and providing facilities for searching specific records.

  • Solving cases where multiple users want to access and potentially change the same data entries.

  • Managing access rights to control who can see or change data.

  • Answering user questions in a reasonable time.

Examples of Database Use

  • Bank: customer data management, accounting, all banking transactions

  • Airport: reservation data management, scheduling

  • Universities: management of registration, alumni

  • Factory: management of production data, inventory ordering

  • Sales: management of customer data, product

  • Telecommunications: management of billing data

Steps in Database Development Process

  1. Planning

  2. Requirement Analysis

  3. System Definition

  4. Logical Model

  5. Database Design

  6. Physical Model

  7. Implementation

  8. Data conversion and loading

  9. Testing

Details of Each Step

Planning

This stage involves planning the entire Database Development Life Cycle.

Requirement Analysis and System Definition

This stage defines the scope and boundaries of the proposed database system.

Logical Model

Developing a database model based on requirements.

Database Design and Physical Model

Implementing the logical model, taking into account the DBMS and physical implementation factors.

Data Conversion and Loading

Importing and converting data from the old system into the new one.

Implementation and Testing

Identifying errors in the newly implemented system.

Data Sharing in Databases

Unlimited Data Sharing

Allows users from different departments to share corporate data according to their information needs.

Properties of Database Systems

A database system consists of logically related data stored in a single logical data repository, which helps eliminate data inconsistency, anomaly, dependency, and structural dependency problems.

It's possible to connect two or more information systems together and transfer data between them.

Properties of Databases

  1. Flexibility

  2. Integrity

  3. Usability

  4. Completeness

  5. Efficiency

Detailed Explanation of Properties

Integrity

Ensures that data is both consistent and correct.

Efficiency

Ensures that users have reasonable response times when accessing data.

Completeness

Ensures that users can access required data.

Flexibility

Ensures that a database can evolve to satisfy changing user requirements.

Usability

Ensures that data can be accessed and manipulated in ways which match user requirements.

Database Management System (DBMS)

Definition

  • Database: A collection of data.

  • Management System (DBMS): A set of programs to store and retrieve the data.

A DBMS is software used to define, manipulate, retrieve, store, and manage data in databases.

Functions of a DBMS

  • A computerized record keeping system.

  • Manages database structure and controls access to the data stored in the database.

  • Allows users to interpret, create, update, arrange, manage, maintain, and control access to the database.

  • Provides an interface between the data and the software application.

  • Allows users to create their own databases as per their requirement.

Key Capabilities of a DBMS

  • Defining rules to validate and manipulate data.

  • Interacting with databases, applications, and end users.

  • Retrieving, storing, and analyzing data.

  • Updating data.

Purpose of DBMS

DBMS software defines a database, stores the data, produces reports, and creates data entry screens.

Core Functions

  1. A database system is a collection of interrelated data and a set of programs that allows users to access and modify the data.

  2. Data is converted into information, and information is then evaluated and organized into knowledge.

  3. A database system adds a new dimension to an organization’s management structure.

Common DBMS Software

MySQL, MariaDB, MS SQL Server, Oracle DBMS, MongoDB, Redis, IBM DB2, Elasticsearch, PostgreSQL, SQLite, Altibase, Teradata, SAP Sybase ASE, ADABAS, FileMaker, MS Access, Informix, AmazonRDS, CouchDB, OrientDB

Traditional Approach to Information Processing

Traditional File Processing System

It's a file-based system where the database is manually handled for updating, inserting, deletion, or adding new files.

Drawbacks

Encourages each functional area in a corporation to develop specialized applications.

Consists of a collection of file folders, each tagged and kept in a filing cabinet.

Keeping track of data in a manual file system became more difficult and time-consuming.

Disadvantages of the Traditional Approach

  1. Data Security: Easily accessible data isn't secure.

  2. Data Redundancy: The same information may be duplicated in multiple files, leading to higher storage and access costs, and data inconsistency.

  3. Data Isolation: Related data is not available in one file, and data is scattered in various files with different formats, making it difficult to share data among different applications.

  4. Program/Data Dependence: No centralized execution of data management functions; data management is scattered among all the application programs.

  5. Lack of Flexibility: If unanticipated data is needed, significant programming effort is required, assuming the information exists in the files.

  6. Concurrent Access Anomalies: Data anomalies develop when not all required changes in redundant data are made successfully; concurrent updates may result in inconsistent data.

Importance of Having a DBMS

  • Improved data security

  • Reduced data redundancy

  • Increased data isolation

  • Increased data consistency

  • Improved data access

  • Increased data sharing

  • Increased end-user productivity

Generic Database Architecture

Centralized Databases

A single database located at one site on a network.

  • Advantages:

    • Easier to get a complete view of data.

    • Easier to manage, update, and backup data.

  • Disadvantages:

    • Bottlenecking from multiple users accessing the same file, slowing down productivity.

Distributed Databases

Consists of two or more files located at different sites on a network.

  • Advantages:

    • Users won't interfere with each other when accessing/manipulating data.

    • Speed since files are retrieved from the nearest location.

    • If one site fails, the system can still run.

  • Disadvantages:

    • Time for synchronization of the multiple databases.

    • Data replication for each different database file.

Three-Schema Architecture of DBMS

The three-schema architecture breaks a database down into three different levels according to its use and structure.

Levels

  1. External/View Level

  2. Conceptual/Logical Level

  3. Internal/Physical Level

Details of Each Level

External/View Level

  • End users’ view of the data environment

  • End users usually operate in an environment in which an application has a specific business unit focus.

Conceptual/Logical Level

  • Represents a global view of the entire database as viewed by the entire organization.

  • Integrates all external views (entities, relationships, constraints, and processes) into a single global view of the entire data in the enterprise.

Internal/Physical Level

  • Describes the way data are saved on storage media.

  • Representation of the database as “seen” by the DBMS.

Client-Server Architecture of DBMS

Definitions

  • Client: A person or an organization using a service; a computer/device (also called a Host) that actually uses the service or accepts the information. Client devices include laptops, workstations, IoT devices, and similar network-friendly devices.

  • Server: A remote computer that provides access to data and services. Usually physical devices such as rack servers. The server handles processes like e-mail, application hosting, Internet connections, printing, and more.

Architecture

Entire files are transferred from the server to the client for processing.

This type of architecture has one or more client computers connected to a central server over a network.

Categories of DBMS

Desktop Databases

MS Access, Fox Pro, FileMaker Pro, Paradox, Lotus

Server Databases

Oracle, MS SQL Server, IBM DB2, Informix

Benefits of Using Desktop Database and Server Solution

Desktop Databases

  • Single-user database supports only one user at a time.

  • Run on personal computers and require no in-depth technical skills.

Server Solution

  • Used by the entire organization and supports many users.

  • Expensive and complex, as they manage vast volumes of data and several users at once.

Detailed Comparison

Feature

Desktop Databases

Server Solution

Management

Easy to use. No knowledge is necessarily needed to be able manage such databases since the programs themselves are normally very intuitive and easy to learn.

Easy Management

Scalability

N/A

Able to gracefully handle a rapidly expanding amount of users and/or data.

Web Solutions

N/A

Provide web solutions so that the user can publish data onto the web in various fashions.

Cost

Inexpensive - Desktop applications are purchased one time and there are not continually occurring charges.

Expensive - as they manage vast volumes of data and several users at once

Flexibility

Can handle just about any data management problem and available for multiple operating systems.

N/A

Performance

N/A

Can manage multiple high- speed processors and high bandwidth connectivity.

The Users of DBMS

  1. End User

  2. Application Programmer

  3. Database Administrator

End User

May not be concerned with or even aware of the details of the DBMS.

Primarily designed for single person to store their data, these databases have simpler structure and functioning as compared to other databases.

Involved in updates to the database or queries on the database.

Application Programmer

Application programmers design, debug, test, and maintain set of programs for the users in order to interact with database.

The back-end programmers who writes the code for the application programs.

Also referred as System Analysts or simply Software Engineers.

Database Administrator

Responsible for problems such as security breaches and poor system response time.

Responsible for providing security to the database and allows only authorized users to access/modify the database.

A person/team who defines the schema and also controls the 3 levels of the database.

Conclusion

Database users are individuals who interact with data.

The access and permissions within a database depends on their function and tasks.

Database users know the value of data security, privacy, and integrity, as well as how to query data from databases using Structured Query Language (SQL) or other tools.