$('#volunteer4').empty();
$.ajax({
type:"post",
url:url,
cache:false,
ifModified:true,
async:true,
success:function(data){
$("#volunteer4").append('<option>全部</option>');
for(var i=0;i<data.length;i++){
var volunteer=data[i];
$("#volunteer4").append('<option value="'+volunteer.codeid+','+volunteer.codeitemname+'" >'+volunteer.codeitemname+'</option>');
}
}
});