麻烦帮忙看看，周末了，怎么不能实现联动呢？盼望解决

Question

public partial class _Default : System.Web.UI.Page 
{
    protected void Page_Load(object sender, EventArgs e)
    {
        string settings = Convert.ToString(ConfigurationManager.ConnectionStrings["SqlConn"]);
        SqlConnection myconn = new SqlConnection(settings);
        myconn.Open();
        string strsql = "select csmc from Table_1";
        SqlCommand cm = new SqlCommand(strsql, myconn);
        SqlDataReader dr = cm.ExecuteReader();
        while (dr.Read())
        {
            DropDownList1.Items.Add(new ListItem(dr["csmc"].ToString()));
        }
        myconn.Close();
    }    protected void DropDownList1_SelectedIndexChanged(object sender, EventArgs e)
    {
                                                        
        string settings = Convert.ToString(ConfigurationManager.ConnectionStrings["SqlConn"]);
        SqlConnection myconn = new SqlConnection(settings);
        myconn.Open();
        string strsql = "select xqmc from Table_2 where csmc=(select csmc from Table_1 where csmc = DropDownList1.SelectedValue)";
        SqlCommand cm = new SqlCommand(strsql, myconn);
        SqlDataReader dr = cm.ExecuteReader();
        while (dr.Read())
        {
            DropDownList2.Items.Add(new ListItem(dr["xqmc"].ToString()));
        }
        myconn.Close();
    }
}

Answer 1

protected void Page_Load(object sender, EventArgs e)
    {
        string settings = Convert.ToString(ConfigurationManager.ConnectionStrings["SqlConn"]);
        SqlConnection con = new SqlConnection(settings);
        con.Open();
        SqlCommand scd = new SqlCommand("select * from Table_1", con);
        SqlDataReader sdr = scd.ExecuteReader();
        this.DropDownList1.DataSource = sdr;
        this.DropDownList1.DataTextField = "csmc";
        this.DropDownList1.DataValueField = "csmc";
        this.DropDownList1.DataBind();
        sdr.Close();        SqlCommand scd1 = new SqlCommand("select * from Table_2 where csmc='" + this.DropDownList1.SelectedValue + "'", con);
        SqlDataReader sdr1 = scd1.ExecuteReader();
        this.DropDownList2.DataSource = sdr1;
        this.DropDownList2.DataTextField = "xqmc";
        this.DropDownList2.DataValueField = "xqmc";
        this.DropDownList2.DataBind();
        sdr1.Close();
    }    protected void DropDownList1_SelectedIndexChanged(object sender, EventArgs e)
    {
        string Name = this.DropDownList1.SelectedValue;
        string settings = Convert.ToString(ConfigurationManager.ConnectionStrings["SqlConn"]);
        SqlConnection con = new SqlConnection(settings);
        con.Open();
        SqlCommand scd2 = new SqlCommand("select * from Table_2 where xqmc ='" + Name + "'", con);
        SqlDataReader sdr2 = scd2.ExecuteReader();
        this.DropDownList2.DataSource = sdr2;
        this.DropDownList2.DataTextField = "xqmc";
        this.DropDownList2.DataValueField = "xqmc";
        this.DropDownList2.DataBind();
        sdr2.Close();
        con.Close();
    }改成这样，只能显示第一个下拉中第一索引中的内容，郁闷，随便第一个下拉怎么变，第二个都不动

Answer 2

没看具体代码，提一点，你第一个下拉框里面是否设置了autopostback=true