You don't really make a game out of SQL. SQL is just a way to access organized data. In other words, just what you want.
You need a presentation layer. Probably a programming language suited for building clients and a graphics API, like DirectX and OpenGL. You will need a server that organizes everything that happens in your world. This is the key part. Speed is of the essence here, probably C++ with heavy networking API use. Winsock comes to mind. The server will need to access all data, your terrain, your monsters, your players, simply ererything. This is going to be a lot of data organized in many different fashions. SQL would be the best way. However, if your game needs to be really cutting egde ( like MMORPG ) accessing a database will be too slow because a database is a generic thingy and you can shortcut many things that a database cannot. Because you know what kind of data you have.
An MMORPG isn't that different from a forum or a blog. Just huge. You have a table for weapons, a table for armour, a table for monsters, a table connecting each monster to a number of weapons and armour, a table for loot, a table connecting each monster to a random number of possible loot items... it goes on and on. But basically, it's tables and connections.
I wouldn't start too big ( though if it starts with M it's already too big ). Get 2 characters going and have them fight each other. Even that's not easy. If you manage, display them graphically. Once you got that done, have each fighter be one program and the server decides the outcome. Once you have done this, you will have started over at least twice. Keep going. And don't expect to have this in acceptable quality in less than 2 years.