如何使用php在多个postgres数据之间添加逗号而不是最后？

my php code is like this:

    <?php 
    require_once 'DBOperations.php';

                    $db = new DBOperations();
                    $data = $db->soilDescription($profile);
    for($j=0; $j<sizeof($data); $j++)
    {

<?php echo $data[$j]['consistence_moist']; ?>, <?php echo $data[$j]['consistence_dry']; ?>, <?php echo $data[$j]['conisitence_wet']; ?> Consistency;
}

Here, some postgres data may be null also. so we don't need ',' in null or empty values. I want output something like this: Plastic, Sticky Consistency;

But, I am getting output like this:

, , Plastic, Sticky Consistency;