DropDownList 绑定数据问题 在线等

Question

SqlDataAdapter da1=new SqlDataAdapter("select*from shopleixing",con);
    DropDownList1.Items.Add(new ListItem("全部"));
    DropDownList1.DataSource=ds.Tables["shopleixing"];
    DropDownList1.DataTextField="leixing_zl";
    DropDownList1.DataBind();这是绑定的代码我想手动加上 全部 并且在最上面显示 可是库里的数据将“全部”给覆盖了
 我样怎么做呢

Answer 1

DropDownList1.Items.Insert(0,new ListItem("全部",""));

Answer 2

DropDownList1.Items.Insert(0,new ListItem("全部");

Answer 3

SqlDataAdapter da1=new SqlDataAdapter("select*from shopleixing",con);
    
    DropDownList1.DataSource=ds.Tables["shopleixing"];
    DropDownList1.DataTextField="leixing_zl";
    DropDownList1.DataBind();
   DropDownList1.Items.Insert(0,"全部");
   DropDownList1.Items[0].Value="";