while ( my $ref = $self->fetch_assoc($sth) )

##</code><code>##

my $dbh = DBI->connect(@db_args);
my $sql = "SELECT email FROM database.table";
my $sth = $dbh->prepare($sql);
$sth->execute();
while (my $hashref = $sth->fetchrow_hashref) {
	...

##</code><code>##

my $sth = $db->query($sql)...