获取tr jquery的td的每个值的动态值

$("#student").find("tr:gt(0)").remove();
for (var i = 0; i < data.length; i++) {
    tr = $('<tr/>');
    tr.append("<td id='id'>" + "<a class=\"school_id\"  id=" + data[i].id + " href='/go.html?url=#' value='" + data[i].id + "'>" + data[i].id + "</a>" + "</td>");
    tr.append("<td id='lastname'>" + data[i].lastname + "</td>");
    tr.append("<td id='firstname'>" + data[i].firstname + "</td>");
    //$("#td_id").attr('width', '15%');
    //$('tr td:nth-child(1)').get(0).style.width = '100px';
    //tr.find('td:nth-child(2)').width('30%');‌​
    $("#student").append(tr);
}
$("#student").find("tr:gt(0)").remove();
for (v