I have a database file with .DB file extension. I have been googling and it looks like SQLite. I tried to connect to it using SQLite and SQLite3 drivers and I am getting an erro
On a Unix-like system (or Cygwin under Windows), the strings
utility will search a file for strings, and print them to stdout. Might help you narrow the field.
There are a lot of programs besides database programs that use a "db" extension, including
and so on. Google "file extensions" for some sites that catalog file extensions and the programs that use them.