Database Design Principles

1. Normalization

Normalization is the process of organizing the data in a database to reduce redundancy and improve data integrity. It involves dividing larger tables into smaller, more manageable tables and defining relationships between them. The most common forms of normalization are First Normal Form (1NF), Second Normal Form (2NF), and Third Normal Form (3NF).

Example:

CREATE TABLE Customers (
    CustomerID INT PRIMARY KEY,
    Name VARCHAR(100),
    Address VARCHAR(255)
);

CREATE TABLE Orders (
    OrderID INT PRIMARY KEY,
    CustomerID INT,
    OrderDate DATE,
    FOREIGN KEY (CustomerID) REFERENCES Customers(CustomerID)
);
    

In this example, the Customers and Orders tables are normalized. The CustomerID in the Orders table is a foreign key that references the CustomerID in the Customers table, ensuring data integrity and reducing redundancy.

2. Entity-Relationship (ER) Modeling

Entity-Relationship (ER) modeling is a graphical approach to database design. It involves identifying entities (objects or concepts) and their relationships within a system. ER diagrams help in visualizing the structure of a database and understanding how different entities interact with each other.

Example:

Consider a university database with entities like Students, Courses, and Professors. The ER diagram would show that a Student can enroll in multiple Courses, and a Course can be taught by multiple Professors. This visual representation helps in designing the database schema effectively.

3. Indexing

Indexing is a technique used to improve the speed of data retrieval operations on a database table. An index is a data structure that stores a sorted list of the contents of a specified column, allowing the database to find data more quickly. Proper indexing can significantly enhance query performance.

Example:

CREATE INDEX idx_customer_name
ON Customers (Name);
    

In this example, an index named idx_customer_name is created on the Name column of the Customers table. This index will speed up queries that filter or sort by the Name column.