Hi,
I .db file is a native h2 database file. It does not need to be imported, as it is simply the database itself, it simply needs to be opened. The are several ways to open and read an h2 .db file, but the easiest way is to use the web interface console. The quick start guide will be your friend here:
http://www.h2database.com/html/quickstart.htmlWhat is your goal with the H2 file, do you just want to read the contents? Read it from a Java app? Something else?
Also, note that other databases also use the .db file extension, so if you do not in fact have a native h2 database file, then the process of loading it into h2 is much more complicated. Let us know where you are getting stuck in the quickstart guide and we will help you out.
-Adam