Chapter 3: Down to the Metal — Understanding JDBC

After setting up the layers, I wanted to see what happened underneath.

How does data actually move between my app and the database.

So instead of relying on tools or abstractions, I decided to go down to the metal — to the JDBC level

💾 Down to the JDBC Level

For education purposes I had to write almost everything myself, using only Spring Boot and Spring Web. I even wrote the SQL manually and took time to understand its syntax.

Back in school, when I used PHP, I never really wrote SQL manually. I mostly used phpMyAdmin in Xampp to create tables or generate queries automatically. Later, most of my personal projects used MongoDB as the main database, so I got comfortable with NoSQL.

This was my first time actually using SQL in a real backend system. I’d learned the basics before —simple queries like SELECT, INSERT and UPDATE — but this was different. Now I had to design tables, define relationshipss, and make every thing work with the backend logic. It gave me a small sense of confident — like I was finally starting to get it.

🔨 Beginning from sctrach

I built the entire project without using tools like Lombok to speed things up. I already knew the concept of ORM (Object Relational Mapping) from theory, but I had never actually used it in practice. I wanted to fully understand the basics first before relying on any tools, so instead of using frameworks like Spring JDBC, Sptring Data JDBC or Spring Data JPA, I decided to go with the raw JDBC API to talk directly to the database — just pure SQL — only a simple DataSource configuration from Spring to handle the connection.

For everything else, I had to do it all by hand — basically reproducing SQL tools do behind the scenes. And oh boy! I had to write queries, open the connections, execute statements, and handle results through ResultSet. I even had to map every record manually. It was easy to understand how things worked, but the boilerplate was enormous — sometimes 20 to 30 lines of code just to run a single query it. Still, it was worth it. It took me days to complete the repository layer.

🚀 Ready for the Next Layer

That experience taught me more than any tutorial ever could.

But the backend was only half the story.

To make everything visible, I had to see it — in action.

Next stop: the frontend