Introduction to Databases - CSC1022

• CSC1022 is an introduction to databases course
• The instructor is Dr. Yalemisew Abgaz at Dublin City University's School of Computing

Outline

• A definition of what a database is
• The usage of a database
• Large databases
• File-based systems
• Database Management Systems
• Components of database systems
• Roles of database users

Definition: Databases

• A database is a collection of related data
• Data consists of known facts that can be recorded and have implicit meaning
• Examples include names, telephone numbers, and addresses
• This data can be recorded in an indexed address book, a hard drive, or using software like Excel
• Flight booking systems, registry systems(student info), and library resource management systems are example databases

Usage

• A database is designed, built, and populated with data for a specific purpose
• Databases have intended users with preconceived applications
• Databases derive data from a source, engage with real-world events, and have an interested audience
• End users perform business transactions or experience events that change database information
• A database must be a true reflection of the real world and changes must be reflected as soon as possible

Large Databases

• Google uses exabytes (~10^18) and zettabytes (~10^21)
• Other examples of large databases:
  • Youtube
  • Amazon
  • World Data Centre for Climate
  • AT&T
  • Library of Congress

File-based Systems

• A collection of application programs that perform services for end users, such as resource production
• Applicable for small databases storing data about a few entities
• Applicable when a stand-alone system is used and doesn't require sophisticated reporting
• File-based systems fail with increasing demands for reports and summaries, requiring a huge effort to generate them or a huge amount of data updates

Problems of File-Based Systems

• Separation and Isolation: Difficult to integrate files and keep track of data when stored separately, which makes synchronisation and utilisation difficult
• Duplication: File-based approach duplicates data, such as lecturer information for both IT and Business students
• Data Dependence: Access relies on the program reading/writing data, making it difficult to read with another program and requiring code changes when the data structure changes
• Incompatible File Format: Compatibility between files of different programming languages is difficult
• Fixed Queries: Difficult to run varied queries due to pre-processed queries and specific functions

Database Management Systems

• DBMS is a program that interacts with the database, allowing users to define, create, maintain, and control access
• Data Definition Languages (DDL) define the database and describe data details and storage
• Data Manipulation Languages (DML) allow users to insert, delete, update, and retrieve data
• Access control features allow users to manage access, maintain security, integrity, recovery, and metadata services

Database Application Program

• A computer program that interacts with the database system using requests to the DBMS
• Views: can view specific data parts, provide security by restricting data from unauthorized users, customize the database appearance, and present a consistent picture of the database

Components of DBMS Environment

• There are 5 major components:
• Hardware: Stores, manipulates, and controls data from a single computer to a Mainframe server
• Software: The DBMS, applications, and network software
• Data: The most important aspect from the user's perspective, containing operational data and metadata
• Procedures: Instructions and rules governing database design and use, including login and back-up procedures
• People: Designers, programmers, and users, categorized into four types

Roles of Database Users

• 4 categories of users: Data and Database Administrators, Database Designers, Application Developers, and End-users

Data and Database Administrators

• Data Administrator (DA): manages the data resource, including planning, development, maintenance of standards, policies, and procedures
• Database Administrator (DBA): focuses on physical realization, design, implementation, security, integrity, maintenance, and performance

Database Designers

• Logical database designer identifies data entities, attributes, relationships, and constraints
• Physical database designer determines how the logical design is physically realized, requiring technical and business knowledge of the target DBMS

Application Developers

• Responsible for building or implementing applications that enable end users to access the database

End-Users

• The "clients" and actual consumers of the database who may be Naive or sophisticated users

An introduction to databases, their usage, and database management systems. Includes components, users, and how they compare to file-based systems. Examples provided are flight booking, registries, and library management systems.