DB is a programming language so what you can do is limited only by your programming skills.
Also, there are different levels of AI. For example, the AI involved in the game of pong is nowhere near the level required for say a Command & Conquer clone or an FPS.
'Artificial Intelligence' sounds really complicated, but broken down to it's basic elements, it's no more than checking for certain conditions in a loop and depending on the result, making a decision on what to do.
The hardest part is applying all those checks to all the necessary components of the game and making the decisions quickly enough to not affect the flow of the rest of the game.
TDK_Man