Database Migration with Flyway
The Problem — Why ddl-auto=update is Dangerous in Production Since Lecture 5, we have been using this configuration: This tells Hibernate: “Compare my entity classes to the database and apply […]
Service Layer Design & Business Logic
Layered Architecture — Controller → Service → Repository We have been using the layered architecture since Lecture 2, but we have never formally defined the rules that govern each layer. […]
DTO Pattern, Validation & Error Handling
Why Not Expose Entities Directly? The DTO Pattern Throughout Lectures 5–7, we returned JPA entities directly from our REST controllers. This worked for learning, but it causes serious problems in […]
Entity Relationships & Advanced Mapping
Relationship Types in Relational Databases In the real world, data is connected. A user writes posts. A post has comments. A post belongs to categories and has multiple tags. Modeling […]
CRUD Operations with Spring Data JPA
Repository Pattern Deep Dive What is the Repository Pattern? The Repository pattern is a design pattern that abstracts data access behind a clean interface. The idea is simple: your service […]
Spring Data JPA & Hibernate Fundamentals
The Problem — Why Not Write Raw SQL in Java? In Lecture 4, you wrote SQL directly in the MariaDB shell. That is fine for database administration, but what about executing SQL from […]
Introduction to MariaDB & Database Setup
1. Why a Relational Database? SQL Refresher The Problem with In-Memory Storage In Lectures 2 and 3, we stored data in Java HashMap and ArrayList. This worked for learning, but it has a […]
Building REST APIs with Spring MVC
1. What is REST? Principles and Constraints In Lecture 1, we briefly mentioned REST APIs. Now let us dive deeper into what REST actually means and why it is the […]
Spring Boot Core Concepts — Dependency Injection & Auto-Configuration
Recap — From Java main() to a Running Web Server In Lecture 1, we created a Spring Boot application with a simple HelloController. Let us quickly revisit what happens when you […]
Introduction to Web Development & Spring Boot
How the Web Works — HTTP Request/Response Cycle Before writing a single line of Spring Boot code, you need to understand what actually happens when you type a URL into […]