No matter how you approach this, there's going to be some significant data-formatting required.

Best approach for what you're asking: use DataTables server-side tools.

It requires including some additional components, but will simplify the javascript down to:

$('#example').DataTable( {
    "processing": true,
    "serverSide": true,
    "ajax": "../server_side/scripts/server_processing.php"
} );

...with a little tweaking, you can simplify that further:

$(function(){
    var dt = new dataTableAuto();
    dt.load();
});

function dataTableAuto() {
    this.params = {
        "processing": true,
        "serverSide": true,
        "ajax": "../server_side/scripts/server_processing.php"
    };

    this.load = function() {
        $('#example').DataTable( this.params );
    }
}

php ajax server to send raw JSON as a single row

Simply send an ajax request to php which includes the counter, then respond with a json array matching what you want to build.

Javascript snippet

counter = 0;

$.ajax({
    url: '[your url]',
    type: 'post',
    data: {"counter":counter},
    contentType: "application/json",
    dataType: 'json',
    success: function(response){
        t.row.add(JSON.parse(response)).draw( false );
        counter++;
    },
});

php Snippet

$jsonString = file_get_contents('php://input');
$data = json_decode($jsonString);
$counter = $data['counter'];
$totalRows = 10;

for( $i = 0; $i < $totalRows; $i++) {
    $result[] = $counter .".". $i;
}

header('Content-Type: application/json', true, 200);
echo json_encode($result);
exit;

DataTables pure AJAX approach

javascript

$(function(){
    t = $('#example');

    $.ajax({
        url: '[your url]',
        type: 'post',
        data: {"classID":12},
        contentType: "application/json",
        dataType: 'json',
        success: function(response){
            t.DataTable( JSON.parse(response) );
        },
    });
});

php

$jsonString = file_get_contents('php://input');
$data = json_decode($jsonString);
$classID = intval($data['classID']);

$cols = array('Name', 'Position', 'Score');
foreach ( $cols as $colName ) {
    $entry = new stdClass();
    $entry->title = $colName;
    $result['columns'][] = $entry;
}

$result = // some query [ex: get rows by class id]

foreach( $result as $row) {
    $thisRow = array();
    foreach ( $cols as $colName ) {
        $thisRow[] = $row['$colName']
    }
    $result['data'][] = $thisRow;
}

header('Content-Type: application/json', true, 200);
echo json_encode($result);
exit;

This should produce an object similar to:

{
    data: [
        ['Joseph Taylor', '22', '90']
    ],
    columns: [
        { title: "Name" },
        { title: "Position" },
        { title: "Score" }
    ]
}