my $query = "SELECT something FROM somewhere";
my $sth = $dbh->prepare($query);
my $rv = $sth->execute;
my $first_result = $sth->fetchrow_hashref;

my $query = "SELECT somethingelse FROM somewhereelse";
my $sth = $dbh->prepare($query);
my $rv = $sth->execute;
my $second_result = $sth->fetchrow_hashref;

... then do something with $first_result and $second_result