PHP MYSQL query help, results not what expected

In

do { echo $row['depicao']; ?>-<?php } 
while ($row = mysqli_fetch_array($query))

$row gets defined after first iteration, and not before. That's why $row['depicao'] outputs nothing. If you had error_reporting on - you would also see a notice.

So, first fix is to define $row first and then output it:

while ($row = mysqli_fetch_array($query)) {
    echo $row['depicao']; 
    echo '-';
}

But in this case your output will be ended with -.

So, one of the solutions is to collect values in array and implode'em:

$values = [];
while ($row = mysqli_fetch_array($query)) {
    $values[] = $row['depicao']; 
}
echo implode('-', $values);

Use while loop instead of do...while

Because when you use do while loop it'll execute once always and then it'll check the condition and that's why you got the - at very first of your result.

So use while loop to check the condition, if true then code under loop will execute otherwise not.

I'll strictly recommend you to learn about loops.

Try using while loop instead of do-while.

<?php while($row = mysqli_fetch_array($query)) { echo $row['depicao'];echo'-';} ?>

The problem with do while is that it executes at least once even if the condition fails. Hence one "-" is printed in beginning even without evaluating the condition.

If the goal is just to remove the extra "-" then it can be done with-

<?php do { echo $row['depicao']; if($row['depicao']!=null) echo "-"; } while ($row = mysqli_fetch_array($query)); ?>