Laurent,
Welcome to the Dothraki/Valyrian forums!
Considering the way Dothraki declension/conjugation works, what you are proposing would certainly be a useful tool.
SQL dumps of the dictionary data are indeed available (updates are uncommon at this time, simply because not much is changing). Other foramts are possible.
I am very unexpectedly up to my rear end in alligators, after returning from a wonderful week at AvatarMeet (we had a Dothraki bloodrider show up at one event!). Give me a few days, and I will give you an SQL dump link. If I don't respond right away, just keep pestering me