Magento

many tables in database i dont know why it exist,if you create a diagram database,it will help developers very much.

You can use reverse engineering feature of the CASE tool you use to get the diagram, though i don’t see any practical advantage of having such a diagram ‘cause right now database is used more like a storage, and almost everything is defined in configs. You can look into etc/config.xml of the module you are interested in if needed.