[zzo38computer]

"I think it might be too much work to parse queries, and the easiest thing to do is to just access a string as query and pass that to the database engine." -- You could also use SQLite virtual table; this allows combining it with other data in the same query; SQLite will then automatically convert your query into a list of constraints, ORDER BY clause, etc, and pass the stuff to your xBestIndex method, which can decide which things the server is capable of using and pass those to the back end, letting SQLite handle the rest of the query itself.