How to insert a div when a value changes from sql query - php

Question

I want to show some titles for two users in each of their "profile div".
Let's say there are five titles belonging to user 1 and only two titles belonging to user 2.
The titles are in a table which I joined through user id.
How can I know when the titles foreign key (the user id) switches from one to two? in other words, how can I check for when I start echoing titles for a new user.
I want to implement a new div when the switch is made, so that the titles belonging to user one can be found in his div, and so on for the other user(s)
Below is my query, it works fine showing my data.
For the sake of simplicity I used an example of two users, but in the future I would have more than two users.
$result = mysqli_query($con,$sqltwo)or die(mysqli_error());
while($row = mysqli_fetch_array($result)) {
echo $row['title'];
echo $row['user_id'];
//I want to echo a new div here when the user_id switches to new
value
//and then echo the new titles data for the new user_id.
echo "<br>";
}
EDIT: A succesful scenario would be an output that looked something like this:
<div class="userone">
title1<br>
title2<br>
title3<br>
title4<br>
title5<br>
</div>
<div class="usertwo">
title6<br>
title7<br>
</div>

Answer 1

It can be done with a basic algorithm :
$current_id = '';
while ($row = mysqli_fetch_array($result)) {
if ($current_id != $row['user_id']) {
//new user detected
$current_id = $row['user_id'];
}
}
And so to fit your needs :
$current_id = '';
while ($row = mysqli_fetch_array($result)) {
if ($current_id != $row['user_id']) {
//ignore the first instance where no div has been created yet
if ($current_id != '') {
echo '</div>';
}
echo '<div class = "user'.$row['user_id'].'">';
$current_id = $row['user_id'];
}
//fill your div with your stuff from current user
echo $row['title'] . '<br>';
}
//check if you have at least one row to deal with, and then close the last opened div
echo '</div>';