How not to insert data into the database with mysqli and php?

Question

I wonder if anyone can help me is that I don’t want to enter in the database values where the title is equal but I’m not getting. With the code below it always inserts in the database, not this filter not allow to insert data with the same title in the database. Note: I must use mysqli. Thank you.

function inserirNaTabelaFilmesRegisto(
        $db, //ponteiro pelo qual se faz o acesso à SGBDR
        $titulo, $urlImagem, $hrefAssistir, $categoria, $classificacao
    )
    {

//var_dump($db);
//$db = estabelecerLigacaoSGBDR();
if ($db!==false){
    $select = "select * from  filme where titulo = '$titulo'";
    if($result = $db->query($select)===true) {
 echo "ERRO!<br><br><br><br><br><br><br><br>";
    }else{
    $q = "insert into ".BD.".".TABELA_FILME;
           $q.=" values (null, '$titulo', '$urlImagem', '$hrefAssistir', '$categoria', '$classificacao');";
    $db->query($q);
    $e = mysqli_errno($db);
    $eM = mysqli_error($db);
    echo $eM;
    if ($e===0){
        return true;
    }
    }
}//if
return false;
}//inserirNaTabelaApontamentosRegisto