Recently Floh posted database system of N3 on his blog। Most of the features are very like to N2'. To maximize its merit, it is good to make a tool for it.
Basically we need three different kind of tool for Entity. Let's see them.
1) Object Palette
2) Object Browser
3) Object Property view
The first thing, "Object Palette" is needed to make an game object in the game world. In most case tree control is sufficient for this purpose. And those information can be retrieved from "_Category" table of database file. It is for creation of an entity in the game world.
The second thing, "Object Browser" contains all game objects list. And those information can be retrieved from "_Entities" table of database file. Tree control is also used for this but it should provide search functionality which used for finding object with its given name.
The last thing, "Object Property view" runs when user double clicked any object in object browser. And it shows all properties of the selected object. As you can guess Property window control is used for this data. Columns of the table in the database file are used to fill entries of the properties.