注意：未定义的变量（选择请求）[重复]

I want you to select some informations from a database table, everything its okey but wen I try it for the first time (whene the table is empty) I see this erro on my web page:

Notice: Undefined variable

I have tried if(isset) but it didn t work:

here is my code:

<?php
$select_date = "SELECT mois,annee FROM objectif";
$select_query_date = mysqli_query($conn, $select_date);

if (isset($select_date)) {
    if (mysqli_num_rows($select_query_date) > 0) {
        $mois_date = array();
        $annee_date = array();
        while ($row = mysqli_fetch_array($select_query_date)) {
            if (!isset($row['0'])) $row['0'] = 0;
            $mois_date[] = $row['0'];
            if (!isset($row['1'])) $row['1'] = 0;
            $annee_date[] = $row['1'];
        }

        print_r($mois_date);
    }
}

if (!in_array($mois, $mois_date) && !in_array($annee, $annee_date)) { //---}

</div>

To test if a key is defined, use array_key_exists('1', $row) : http://php.net/manual/fr/function.array-key-exists.php