Since QDB uses SQLite as a backend, I would argue that this will impose the same issues than with using SQLite raw.
A search on ISO 26262 compliant databases doesn't give a lot of hits, I guess that the standard is so new that you won't
 find a lot of mature products that have been developed to this standard simply because the standard wasn't there.
Whatever product you select, you will probably need to do an evaluation yourself, and will prpbably need the 
manufacturers input to this end. There are several companies out there that specialize in embedded database development.
 ITTIA comes to my mind, but there may be others.
You could also try to contact the company behind SQLite to see what comes form their end.

Regards,
Albrecht