DropDownList 获取的值存到数据库变成System.Web.UI.WebControls.DropDown

public partial class cpruku : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {
        Init_data_type();
    }
    protected void Init_data_type()
    {
        if (!IsPostBack)
        {
            ddl_lb.DataSource = DBHelper.GetDataSet("select Type_id,Type_name from Type");
            ddl_lb.DataTextField = "Type_name";
            ddl_lb.DataValueField = "Type_id";
            ddl_lb.DataBind();
        }
    }
    protected void btn_tj_Click(object sender, EventArgs e)
    {
        string str_xh = txt_xh.Text.Trim();
        string str_mc = txt_mc.Text.Trim();
        string str_lb = ddl_lb.SelectedValue.Trim();
        string str_dw = txt_dw.Text.Trim();
        string str_bz = txt_bz.Text.Trim();

        string sql = "insert into  chengpin(xinghao,mincheng,type_id, danwei ,beizhu)values('" + str_xh + "','"+str_mc+"','"+ddl_lb+"','"+str_dw+"','"+str_bz+"')";
        if (DBHelper.ExecuteCommand(sql) >= 1)
        {
            Label1.Text = "添加成功！如果要入库请<a href=''>点击这里";
            txt_bz.Text = null;
            txt_dw.Text = null;
            txt_mc.Text = null;
            txt_xh.Text = null;
        }
        else
        {
            Label1.Text = "添加失败！";
        }
    }
} --------------------编程问答-------------------- string sql = "insert into chengpin(xinghao,mincheng,type_id, danwei ,beizhu)values('" + str_xh + "','"+str_mc+"','"+str_lb+"','"+str_dw+"','"+str_bz+"')";

你写错了，不是ddl_lb，而是str_lb --------------------编程问答-------------------- 楼上正解，你这个编译都会提示你错了吧。

补充：.NET技术 ,  C#