Lecture 1: Introduction to Database Concepts

1. What is a Database?

A Database is not just a random collection of files; it is a structured collection of related data organized in a way that makes it easy to access, manage, and update.

• VS. Traditional Methods: unlike unorganized methods (like random papers or simple text files), a database provides a logical structure.
• VS. Excel: While Excel spreadsheets can store data, databases are designed for larger volumes, multi-user access, and complex relationships.

2. Structure of a Database

In a relational database (which is the focus of this course), data is organized into Tables.

• Table: The main object that stores data. It represents a specific entity (e.g., a "Student" table, a "Product" table).
• Columns (Fields/Attributes): These are the vertical parts of the table. Each column represents a specific piece of information (Data Type) about the entity (e.g., Student_Name, Phone_Number, Age).
• Rows (Records): These are the horizontal parts of the table. Each row represents a single, unique instance or entry of data (e.g., data for one specific student).

3. Key Concepts

• Primary Key (PK): A specific field (or combination of fields) that uniquely identifies each record in a table.
  • Rule: It cannot contain duplicate values and cannot be empty (Null).
  • Example: Student_ID or National_ID. No two people can have the same ID.

4. Database Management System (DBMS)

A DBMS is the software system used to create, manage, and manipulate databases. It acts as an interface between the end-user and the data.

• Main Functions:
  1. Data Definition: Creating tables and structures.
  2. Data Manipulation: Adding, editing, and deleting data.
  3. Data Security: Controlling who can access the data.
• Components of a DBMS:
  1. Hardware: The physical devices (servers, hard drives) storing the data.
  2. Software: The DBMS program itself (e.g., Microsoft Access, MySQL, Oracle, SQL Server).
  3. Data: The actual information stored.
  4. Users: The people interacting with the system (Database Administrators, Designers, End-users).

5. Popular DBMS Software

• Microsoft Access: Good for small to medium desktop applications.
• MySQL: Highly utilized, open-source, used for web applications.
• Oracle: Enterprise-level, powerful and secure.
• SQL Server: Microsoft's enterprise solution.