my $user_login_name = 'name.surname@company.com';

my $sth = $dbh->prepare("SELECT userid, login_name, realname FROM profiles WHERE login_name=$user_login_name"); 

$sth->execute();

while(my @zeile_user = $sth->fetchrow_array())
{
	$user_id_custom 			= $zeile_user[0];
	$login_name_custom			= $zeile_user[1];
	$realname_custom			= $zeile_user[2];
}

##</code><code>##

DBD::mysql::st execute failed: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '@company.com' at line 1 [for Statement "SELECT userid, login_name, realname FROM profiles WHERE login_name=name.surname@company.com"] at C:/Bugzilla/buglist.cgi line 1079