Appear A Picture Which User Input In Web PHP Using Database - php

Question

Can anyone help me out? So, now I'm making a website, and one of the feature there is profile feature. In there I want user can upload their own picture, but if the value is null, then I want the picture is from the default image from mine. But I got a problem when I get the value of the pictures in database. I use a loop to determine whether the value is null or not, but all the images just appear from all the users images, not as the login user.
Here's the php code :
<?php
$arrayPictures[] = array();
$row=0;
while ($result= mysqli_fetch_object($query)) {
$arrayPictures[] = $result->pictures;
$row++;
}
for($i=0;$i<=$row;$i++)
{
if($arrayPictures[$i] == null)
{
?>
<img src="mypath\default.jpg" class="pictures" alt="">
<?php
}
else {
?>
<img class="pictures" src="mypath\<?php echo "$arrayPictures[$i]";?>" >
<?php
}
}
?>
So, what I want is if I login as 'User A', I just want to get the pictures from user A. But If User A not yet upload the pictures, I want to use the default pictures from mine.
This is the query code :
$id_account = $_SESSION['id'];
$query = mysqli_query($con, "SELECT * FROM t_akun WHERE username=$id_account");