easyui动态生成双列头

实习时老大交给任务,让我做这样一个效果,选择日期并点击查询时,动态生成列头,下一列要求对应日期的星期.

效果图:

下面贴出查询的单击函数:

//查询按钮
        function queryByDate(){
            var begin_Date=$('#dateid').datebox('getValue')+"-01";
            var year=begin_Date.substring(0,4);//获取年
            var month=begin_Date.substring(5,7);//获取月
            var max=new Date(year,month,0).getDate(); //选中年月的最大天数
            var columns = [];
            var col = [];
            var col2=[];
             $.ajax({
                       type:"post",
                       url:"/mylog/mobileManage/select.do",
                       dataType:"json",
                       data:{begin_Date:begin_Date},
                       success:function(data){
                           var json = eval("(" + data + ")");
                           col.push({title:"类型",rowspan:2,width:60,field:'type'});
                              col.push({title:"姓名",rowspan:2,width:60,field:'name'});
                             for(var i=1;i<=max;i++){
                           var field='code'+i;
                               var c1 = {title:i,width:40,rowspan:1};
                               var week=getDateWeek(year,month,i);
                               var c2={align:'center',title:week,width:40,rowspan:1,field:field};
                               col.push(c1);
                               col2.push(c2);
                           }
                          columns[0]=col;
                          columns[1]=col2;
                           $('#dg').datagrid({title:"员工工作详情",columns:columns});
                           $('#dg').datagrid('loadData',json);
                           //$('#dg').datagrid('reload');
 
                       }
                   }) ;
        } 
 
function getDateWeek(year,month,day)
        {
            var dateInfo = new Date(year, month-1, day);
            var week = "";
             switch(dateInfo.getDay())
             {
                case 0:
                    week="日";
                    break;
                case 1:
                    week="一";
                    break;
                case 2:
                    week="二";
                    break;
                case 3:
                    week="三";
                    break;
                case 4:
                    week="四";
                    break;
                case 5:
                    week="五";
                    break;
                case 6:
                    week="六";
                    break;
             }
             return week;
        }