An opening database is possible, because the beginning position is the same. But an endgame database is not possible, as the variety of positions is mind-boggling. Why, for only 2 kings and 1 pawn endings alone, the number of possible positions are close to 208,308!
What you can do is consult an authoritative book on endings (e.g.: Basic Chess Endings by Ruben Fine - there are several others). Practicing against the computer may help, but I do not know which softwares excel in endings.
Please can we have an endgame database, along the same lines as the game explorer? The game explorer is really useful but I need to practice my endgames. All I want is to be able to click and drag some pieces onto the board and have some helpful analysis. I've looked on the interweb but it's all funny tables and codes.