Databases are used to store and manage large amounts of organized information. This guide explains the fundamental concepts.

1. Short Notes: Core Concepts

a) Database Fundamentals

• Database: An organized collection of data.

• Table: The core object where all data is stored, organized into columns and rows.

• Field: A single column in a table (e.g., First_Name). Each field has a Data Type (Text, Number, Date/Time).

• Record: A single row in a table, representing a complete set of information for one item.

b) Relational Databases & Keys

• A relational database stores data in multiple related tables to avoid data duplication (redundancy).

• Keys are used to uniquely identify records and link tables.

  • Primary Key: A field that contains a unique value for each record in a table (e.g., Admission_No). It cannot be empty.

  • Foreign Key: A field in one table that is the primary key in another table. It is used to link the two tables together.

c) Table Relationships

• One-to-Many: One record in Table A can be linked to many records in Table B. This is the most common relationship.

  • Example: One Teacher can have many Students. The Teacher_ID (primary key) would be a foreign key in the student table.

d) Database Management System (DBMS) Objects

• A DBMS (like Microsoft Access) is the software used to create and manage databases.

• Forms: User-friendly interfaces for entering, viewing, and editing data.

• Queries: Used to ask questions and retrieve specific information from the database by setting criteria.

  • Example Query: "Show all students whose City is 'Kandy'."

• Reports: Used to format and present data in a professional, printable layout. You cannot edit data in a report.

2. Tips and Tricks for the Exam

• Key Analogy: Think of a library. The entire library is the Database. A shelf of books is a Table. A single book is a Record. The book's title and author are Fields. The unique ISBN is the Primary Key.

• Primary vs. Foreign Key: The Primary Key is the "master key" for a table. The Foreign Key is a "copy of the master key" used in another table to create a link.

• DBMS Object Tip:

  • Table = Stores data.

  • Query = Asks questions.

  • Form = Inputs/Edits data.

  • Report = Outputs/Presents data.

3. Important Points to Remember

• The main purpose of a relational database is to minimize data redundancy.

• A Primary Key must be unique for every record.

• A One-to-Many relationship is the most common type to understand for your exam.

• You use a Query to find data and a Report to print it nicely.