php chat duplicate users prevent - php

Question

i have problem, on my code i create chat, but duplicate users name, i try prevent but not success.... some can help?
my code:
$sql = "SELECT * FROM `inbox` WHERE `from`='".$_SESSION['username']."' OR `to`='".$_SESSION['username']."' ORDER by `data` DESC;";
$result = mysqli_query($conn, $sql) or die(mysqli_error($conn));
$lastuser = "";
while($row = mysqli_fetch_array($result)) {
$chat_name = "";
if($row['from'] == $_SESSION['username']) {
$chat_name = $row['to'];
} else {
$chat_name = $row['from'];
}
if($lastuser != $chat_name) {
echo "
<a href='?user=".$chat_name."'>
<div class='inbox_users_box'>
<div class='inbox_imagenuser'>
<img class='inbox_image' src='".getAvatarOthers($chat_name)."'></img>
<div style='margin-top: 14px; float: left;'>".$chat_name."</div><span style='margin-top: 17px; margin-left: 5px;' class='".getonline_player($chat_name)."'></span>
<div style='clear:both;'></div>
</div>
<div class='inbox_lastmsgdata'>".$row['data']."</div>
</div>
<div style='clear:both;'></div>
</a>
";
$lastuser = $chat_name;
}
}
my chat : my chat picture
i want dont duplicate users..

Answer 1

You can save the filtered inbox entries in an array with the data to display, but only when the user isn't already in that array. This way it gets added only once. After that you print the array the way you like with a normal foreach() loop.
$users = array();
while ($row = mysqli_fetch_assoc($result);
// retrieve the data from MySQL
$chat_name = "";
if($row['from'] == $_SESSION['username']) {
$chat_name = $row['to'];
} else {
$chat_name = $row['from'];
}
$data = $row['data'];
// look if the user is already in the array
$found = false;
foreach ($users as $user) {
if ($user['name'] == $chat_name) {
$found = true;
break;
}
}
if ($found) {
continue;
}
// its not, so add it
$toAdd = array('name' => $chat_name, 'data' => $data);
$users[] = $toAdd;
}
/* display users */
foreach ($users as $user) {
$username = $user['name'];
$data = $user['data'];
// your HTML code here
}