Introduction to Databases and DBMS

Study Notes

Lecture 1 introduces databases (DB) and Database Management Systems (DBMS)
Concepts covered in the course include DB and DBMS, characteristics of DB, database users, database models, ER Model, Relational DB Schema, Database Normalization, Relational Algebra, Database Concurrency, and Lock Conversion.
The reference textbook for the course is "Fundamentals of Database Systems" by Ramez Elmasri and Shamkant B. Navathe, Sixth Edition.

Databases are used in various settings, including banks, hotels, libraries, and supermarkets.

Traditional database applications primarily store and access textual or numeric information.

Multimedia databases store images, audio clips, and video streams digitally.
Geographic Information Systems (GIS) store and analyze 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 from large databases for decision-making.
Database search techniques are applied to the WWW to improve information retrieval for Internet users.

A database is a collection of related data, which consists of known, recordable facts with implicit meaning.
This can be exemplified by names, phone numbers, and addresses stored using software.

A database represents a real-world aspect, known as the miniworld or the universe of discourse (UoD).
Changes to the miniworld are reflected in the database.
A database is designed, built, and populated with data for a specific purpose and user group.
Databases are logically coherent collections of data with inherent meaning, can vary in size and complexity.

A DBMS is a collection of programs enabling users to create and maintain databases.
It is a general-purpose software system that facilitates defining, constructing, manipulating, and sharing databases among various users and applications.

Defining a database involves specifying data types, structures, and constraints.
Database definitions are stored by the DBMS as meta-data in a database catalog or dictionary.
Constructing a database is storing data on a storage medium controlled by the DBMS.
Manipulating a database includes querying, updating to reflect changes, and generating reports.
Sharing a database allows multiple users and programs to access it simultaneously.

Application programs access the database by sending queries to the DBMS, where a query retrieves data.

Protecting the database involves system protection against hardware/software malfunction and security protection against unauthorized access.
Maintaining the database involves adapting the system to evolving requirements over time, because large databases have long lifecycles.

It is possible to create a special-purpose DBMS software by coding your own management system.

A UNIVERSITY database contains information about students, courses, and grades
Defining this database specifies data types for each record in each file
Each COURSE record, for example includes data to represent the Course_name, Course_number, Credit_hours, and Department

Name of STUDENT is a string of characters
Student_number is an integer
Grade of GRADE_REPORT is in the set {'A', 'B', 'C', 'D', 'F', 'I'}
Class of STUDENT is: 1 for freshman, 2 for sophomore, 3 for junior, 4 for senior, and 5 for graduate student.
Constructing the UNIVERSITY database involves storing data to represent each student, course, section, grade report, and prerequisite as a record in the appropriate file.
Database manipulation involves querying and updating.
Examples of queries: retrieve a list of courses and grades for ‘Smith’; list students in the ‘Database’ course in fall 2008 and their grades; list the prerequisites of the ‘Database’ course.
Examples of updates: Change the class of ‘Smith’ to sophomore (2); create a new section for the ‘Database’ course; enter a grade of ‘A’ for ‘Smith’ in the ‘Database’ section.