مفاهيم قواعد البيانات، المحاضرة 1

Study Notes

This document is about Database Concepts, Lecture 1, presented by Professor Fatima Abdul-Baqi Muhammad.

Databases are used in banks, hotels, libraries, and supermarkets.
These interactions are samples of the traditional database applications, where information is stored and accessed in text or digital forms.
Technological advances are leading to new and exciting database systems applications.

Multimedia databases store images, sound clips and video streams digitally.
Geographic Information Systems (GIS) store and analyze weather maps, data, and satellite images.
Active and Real-time Databases: Used to control industrial and manufacturing operations.

Data warehouses and online analytical processing (OLAP) are used to extract and analyze business information for decision-making.
Database search technologies are applied to the Internet to improve information retrieval for users.

A database is a collection of related data representing known facts that can be recorded.
This data is stored as records with implicit meaning and relevant information.
Names, phone numbers, and addresses are examples of data stored, organized in indexed address books, or saved digitally using programs like Microsoft Excel or Access.
A database represents real-world aspects, referred to as the miniworld, and changes in the miniworld are reflected in the database.
A database is a logically coherent data set with inherent meaning; a random data collection cannot be considered a database.
A database is designed for specific purposes, has a target user group, and specific applications of interest to its users.
Databases can vary widely in size and complexity.

A database management system (DBMS) is a set of programs allowing users to create, manage, and maintain databases.
A DBMS is a software system simplifying the definition, creation, manipulation, and sharing of databases among users and applications.

Defining a database involves specifying data types, structures, and constraints.
Database definitions or descriptive information are typically stored as metadata in a database catalog or dictionary.
Creating a database involves storing the data on a storage medium, which is controlled by the DBMS.

Processing a database includes functions like retrieving specific data via queries, updating to reflect changes, and generating reports.
Database sharing enables multiple users and programs to access the database simultaneously.

Applications access the database by sending data requests to the DBMS. These transactions may involve reading data, writing data, or both.
Database systems must ensure database protection and maintenance over time.

Protection includes security measures against hardware/software malfunctions, unauthorized use, and malicious access.
Maintenance involves maintaining the database system by allowing it to evolve to meet changing requirements over time.
Custom database management systems can be built for specific purposes, which involves creating specialized programs designed to manage proprietary databases.

To consider are databases that maintain information about students, courses, and grades in a university environment.
Example Database structure and data models are provided.

To define this database, the structure of records in each file must be specified by defining the data elements and their types in each record.
For instance, each COURSE record includes the course name, number, credit hours, and department offering the course.
The type of data for each data element within a record has to be defined, such as the student's name being a string and the student number being an integer.
Coding schemes can be used to represent data element values, such as using numerical values to represent a student's year.

To create a university database, store data to represent each student, course, department, grade report, and prerequisites in the appropriate file.
Records in different files can be related

Examples include retrieving all courses and grades for a specific student, listing names of students enrolled in a "Database" course in Fall 2008 with their grades, or listing prerequisites for the "Database" course.
Updates include changing the class of a student, creating a new section for a "Database" course, or entering a grade for a student in the "Database" course.