PHP循环增量

I have a PHP loop generating a dataset for a chart. It queries two fields I have in a database table.

<?php

    $server = "myserver:1234";
    $user="dbuser";
    $password="userpass";  
    $database = "dbname";

    $connection = mysql_connect($server,$user,$password);
    $db = mysql_select_db($database,$connection);

    $query = "SELECT X, Y FROM dbtable";
    $result = mysql_query($query);        

    while($row = mysql_fetch_assoc($result))
    {
        $dataset1[] = array($row['X'],$row['Y']);
    }
    $final = json_encode($dataset1,JSON_NUMERIC_CHECK);

?>  

Currently data in X is meaningless (it's actually an ID column), and a number increment of 1 starting at 1 will be more useful. This is because I only want to plot a line chart, where X values are fixed. ID would be fine but the values put distracting axis labels on my chart.

How can I use PHP to generate this instead of the database select that I currently have?

Many thanks:)

Declare a variable outside your loop and increment it on each iteration:

$i = 1;
while($row = mysql_fetch_assoc($result))
{
    $dataset1[] = array($i, $row['Y']);
    $i++;
}