假设你已经得到数据集DataSet dsMark

DropDownList1.DataSource = dsMark.Tables[0];
DropDownList1.DataTextField = DropDownList1.valueField = "mark";
DropDownList1.DataBind();

foreach (ListItem item in DropDownList1.Items)
{
    item.text = (item.value == "y") ? "填写完成" : "正在填写";
}

ListItem topItem = new ListItem("全部显示", "all");
DropDownList1.Items.Insert(0, topItem);