PHP: Don't echo a variable in a while loop IF it's a duplicate

Question

I have a variable in an SQL query-based while loop. e.g:

$sql = mysql_query("SELECT * FROM table");
while($row=mysql_fetch_array($sql)){

    echo $row['row'];

}

The while loop is functional and works, however the variable contains duplicate strings.

How do I prevent duplicate row variables echoing in my while loop with PHP?

Note: This is a PHP question, not an SQL question.

Answer 1

Just keep track of each row's unique ID. If you see again, skip it.

$sql = mysql_query("SELECT * FROM table");
$ids = array();
while($row=mysql_fetch_array($sql)){
    if (!isset($ids[$row['id']])) {
        continue;
    }
    $ids[] = $row['id'];
    echo $row['row'];

}

FYI, this is a lot easier and faster if you do it in SQL. But if you must do it in PHP this is how you would do it.