I Was Confused About Merise for Weeks. Here's Everything I Learned

When I started learning database design, my teacher kept saying "MCD, MLD, MPD" and I had no idea what any of that meant. I searched in English and found almost nothing. That's when I realized Merise is a French methodology, and most of the internet doesn't talk about it. So I learned it the hard way. This is the guide I wish existed when I started. What is Merise? Merise is a French software and database design methodology created in the 1970s-80s. It's widely used in France and French-speaking countries, but almost unknown in the English-speaking world where people use ERD or UML instead. The core idea of Merise is that you design your database in 3 levels, going from abstract to concrete: Level French Name English Equivalent MCD Modèle Conceptuel de Données Conceptual Data Model MLD Modèle Logique de Données Logical Data Model MPD Modèle Physique de Données Physical Data Model Think of it like building a house: MCD = the architect's sketch (ideas, no technical details) MLD = the blu