Introduction to Databases

Introduction to Databases

• Banks, hotels, libraries, and supermarkets are places where databases are used
• Traditional database applications store and access mostly textual or numeric information
• Technology advancements drive new database system applications
• Multimedia databases store images, audio, and video digitally

Geographic Information Systems (GIS)

• GIS stores and analyzes maps, weather data, and satellite images
• Real-time and active database technology controls industrial and manufacturing processes
• Data warehouses and online analytical processing (OLAP) extract and analyze business information to support decision-making
• Database search techniques are being applied to the WWW to improve information search for Internet users

Database Defined

• A database is a collection of related data which represents known, recordable facts with implicit meaning
• Names, telephone numbers and addresses can be stored on hard drives, using software
• This collection is an example of a database

Database Properties

• A database represents some aspect of the real world, often called the miniworld or the universe of discourse (UoD)
• Changes to the miniworld are reflected in the database
• It is a logically coherent collection of data with inherent meaning, not a random assortment
• Databases are designed, built, and populated for a specific purpose with an intended user group and applications
• A database can be of any size and complexity

Database Management System (DBMS)

• A DBMS is a collection of programs allowing users to create and maintain a database
• The DBMS facilitates defining, constructing, manipulating, and sharing databases among various users and applications

Typical DBMS Functionality

• Defining a database includes specifying data types, structures, and constraints
• The database definition, or metadata, is stored by the DBMS in a database catalog or dictionary
• Constructing the database involves storing data on a storage medium controlled by the DBMS
• Manipulating a database includes querying, updating, and generating reports

Functionality of DBMS

• Sharing a database allows multiple users and programs to access it simultaneously
• Programs access the database by sending queries or requests to the DBMS
• A query retrieves data, while a transaction reads and writes data to the database
• DBMS protects the database through system protection against malfunctions and security protection against unauthorized access

Maintaining a Database

• Maintaining a database with a lifecycle of many years necessitates DBMS's ability to evolve as requirements change

Special-Purpose DBMS

• Custom program sets can create and maintain a database like a special-purpose DBMS
• Most DBMSs are complex software systems
• The database and DBMS software together create a database system

Database Example

• A university database maintains information about students, courses, and grades
• Defining requires specifying the file records' structure and data element types
• The COURSE record includes Course_name, Course_number, Credit_hours, and Department
• Data types must be specified for each data element within a record
• Student_number is an integer and grade of GRADE_REPORT is a single character
• Student class is represented by a coding scheme (e.g., 1 for freshman)
• Constructing the database involves storing data for each student, course, etc.
• Records in files may be related