Within QlikView, you can LOAD the QVD file, using almost the same syntax as in a SQL SELECT - you can use WHERE, GROUP BY and ORDER BY clauses. In this sense, - yes, you can load QVD data almost in the same way you query a SQL database. Some details like Joining, need to be taken care of differently...
Outside of QlikView - no, you can't query a QVD file. There is no tool or driver (that I know of) that can read QVD files outside of QlikView.
