DataTables如何在具有ajax数据源的表中添加行号

<link rel="stylesheet" type="text/css" href="https://cdn.datatables.net/1.10.25/css/jquery.dataTables.min.css">
<script src="https://cdn.datatables.net/1.10.25/js/jquery.dataTables.min.js"></script>

<table id="example" class="display" style="width:100%"></table>

$(document).ready(function() {
    $('#example').DataTable({
        "ajax": "data.json", // 替换为实际的ajax数据源URL
        "columns": [
            { "data": "row_number", "title": "行号" }, // 行号列
            { "data": "column1", "title": "列1" },
            { "data": "column2", "title": "列2" },
            // 其他列...
        ],
        "columnDefs": [
            { "orderable": false, "targets": 0 } // 行号列不可排序
        ],
        "order": [[ 1, "asc" ]] // 默认按第2列升序排序
    });
});