$link = mysqli_connect(...) or die("Error " . mysqli_error($link));
$query = "SELECT * FROM MMT_BOT WHERE CHAT_ID = '".$_POST["chat"]."'" or die("Error in the consult.." . mysqli_error($link));
$result = mysqli_query($link, $query);
$res_num = mysqli_num_rows($result);
if ($res_num === 0) {
$query = "INSERT INTO MMT_BOT (CHAT_ID, SESSION) VALUES ('".$_POST["chat"]."','".$_POST["session"]."')" or die("Error in the consult.." . mysqli_error($link));
$link->query($query);
$query = "SELECT * FROM MMT_BOT WHERE CHAT_ID = '".$_POST["chat"]."'" or die("Error in the consult.." . mysqli_error($link));
$result = mysqli_query($link, $query);
} else {
$query = "UPDATE MMT_BOT SET SESSION = '".$_POST["session"]."' WHERE CHAT_ID = '".$_POST["chat"]."'" or die("Error in the consult.." . mysqli_error($link));
$link->query($query);
$query = "SELECT * FROM MMT_BOT WHERE CHAT_ID = '".$_POST["chat"]."'" or die("Error in the consult.." . mysqli_error($link));
$result = mysqli_query($link, $query);
}
$rows = array();
while ($row = mysqli_fetch_array($result, MYSQLI_ASSOC)) {
$rows[] = array('sessione' => $row['SESSION'],'chat_id' => $row['CHAT_ID']);
}
echo json_encode($rows);