use DBI;

...

my $dbh = DBI->connect($dsn, $usr, $pwd, \%attr);
my $stm = 'SELECT <something> FROM <something><etc>';
my $sth = $dbh->prepare($stm);
$sth->execute;
while (my $row_of_data = $sth->fetchrow_arrayref) {
     ...process data, ie, append each row to variable...
}

...

__END__