$dbh = DBI->connect( "DBI:mysql:database=traffic;host=localhost" , "username" ,  "", 'RaiseError' => 1 });

my $sth = $dbh->prepare_cached('SELECT host FROM host WHERE ip = ?')
     or die "Couldn\'t prepare statement: ", $dbh->errstr;
$sth->execute($ip) 
     or die "Couldn't execute select host from host: ", $sth->errstr;		
     my ($host) = ($sth->fetchrow_array());
     undef $sth;