An Example Session

     | ?- db_open(tempdb, update, [a(+,-)], DBRef), assert(tempdb(DBRef)).
     DBRef = '$db'(1077241400)
     
     | ?- tempdb(DBRef), db_store(DBRef, a(b,1), _).
     DBRef = '$db'(1077241400)
     
     | ?- tempdb(DBRef), db_store(DBRef, a(c,2), _).
     DBRef = '$db'(1077241400)
     
     | ?- tempdb(DBRef), db_fetch(DBRef, a(b,X), _).
     X = 1,
     DBRef = '$db'(1077241400) ? ;
     no
     
     | ?- tempdb(DBRef), db_enumerate(DBRef, X, _).
     X = a(b,1),
     DBRef = '$db'(1077241400) ? ;
     X = a(c,2),
     DBRef = '$db'(1077241400) ? ;
     no
     
     | ?- db_current(DBName, Mode, Spec, EnvRef, DBRef).
     Mode = update,
     Spec = [a(+,-)],
     DBRef = '$db'(1077241400),
     DBName = tempdb,
     EnvRef = none ? ;
     no
     
     | ?- tempdb(DBRef), db_close(DBRef).
     DBRef = '$db'(1077241400)