Hi Jan,
reading you, i don't think you are "only beginner"....
Thank you very much for your very clear answer. I will try all your suggest because i'm very interested to better know how osmdroid library work. As true i've found a workaround, also because my best is not use MOBAC (better explain, i need to convert an offline map generated by others gis. Beyond online maps, MOBAC can do it adding different xml, but also here i've found some difficult).
My workaround is simply use mbtiles format. I think is not much different by sqlitedb, but using mbtiles format osmdroid work correctly. And of course i could generate it from alot of gis.
About your explain, me too i've tried to analize content of sqlite db and i've found someting "wrong". But not able myself to say "what's wrong". o your reply is very intresting and i think could help others like me are "really" beginners.
So thank you again. Instead your explanation, i will mark this post as "solved", if moderators are in accord.
Always sorry for my english....
Maurizio.