qt - good combination of a c++ toolkit/library, cross platform db (not necessarily sql) -

What do you suggest as a cross-platform "almost all included" intuitive toolkit / library, not necessarily GUI-oriented?

This project should include at least some web server and some type of "DB" (originally indexed / BTRI, maybe relationships, at some point, hence an RDBM is indispensable, but if necessary , SQL may be overkill)

I was thinking about qt, boost, tokyo cabinet and / or sqlite; what else?

I would like to have at least stage optimization and overall performance footprint ...

Thank you in advance