C# 将值从数据库插入dropdownlist失败

我有州和市的下拉列表（级联），如下所示：

 protected void BindStateDropDown()
{
    string CS = ConfigurationManager.ConnectionStrings["SportsActiveConnectionString"].ConnectionString;
    using (SqlConnection con = new SqlConnection(CS))
    {
        con.Open();
        SqlCommand cmd = new SqlCommand("select * from tblState", con);
        SqlDataAdapter da = new SqlDataAdapter(cmd);
        DataSet ds = new DataSet();
        da.Fill(ds);
        ddlState.DataSource = ds;
        ddlState.DataTextField = "StateName";
        ddlState.DataValueField = "StateId";
        ddlState.DataBind();
    }
    ddlState.Items.Insert(0, new ListItem("---Select---", "0"));
    ddlCity.Items.Insert(0, new ListItem("---Select---", "0"));
}


protected void ddlState_SelectedIndexChanged(object sender, EventArgs e)
{
    int StatId = Convert.ToInt32(ddlState.SelectedValue);
    string CS = ConfigurationManager.ConnectionStrings["SportsActiveConnectionString"].ConnectionString;
    using (SqlConnection con = new SqlConnection(CS))
    {
        con.Open();
        SqlCommand cmd = new SqlCommand("spCities", con);
        cmd.Parameters.AddWithValue("@StatId", StatId);
        cmd.CommandType = CommandType.StoredProcedure;
        SqlDataAdapter da = new SqlDataAdapter(cmd);
        DataSet ds = new DataSet();
        da.Fill(ds);
        ddlCity.DataSource = ds;
        ddlCity.DataTextField = "CityName";
        ddlCity.DataValueField = "CityId";
        ddlCity.DataBind();
    }
    ddlCity.Items.Insert(0, new ListItem("---Select---", "0"));
}

 ddlState.SelectedIndex = ddlState.Items.IndexOf(ddlState.Items.FindByText(rdr["State"].ToString()));
 ddlCity.SelectedIndex = ddlCity.Items.IndexOf(ddlCity.Items.FindByText(rdr["City"].ToString()));

我使用它将值插入数据库，如下所示：

 cmd.Parameters.AddWithValue("@State", ddlState.SelectedItem.Text);
 cmd.Parameters.AddWithValue("@City", ddlCity.SelectedItem.Text);

这很好，可以在数据库表中插入州和城市。现在，我尝试在编辑页面上显示值，如下所示：

 protected void BindStateDropDown()
{
    string CS = ConfigurationManager.ConnectionStrings["SportsActiveConnectionString"].ConnectionString;
    using (SqlConnection con = new SqlConnection(CS))
    {
        con.Open();
        SqlCommand cmd = new SqlCommand("select * from tblState", con);
        SqlDataAdapter da = new SqlDataAdapter(cmd);
        DataSet ds = new DataSet();
        da.Fill(ds);
        ddlState.DataSource = ds;
        ddlState.DataTextField = "StateName";
        ddlState.DataValueField = "StateId";
        ddlState.DataBind();
    }
    ddlState.Items.Insert(0, new ListItem("---Select---", "0"));
    ddlCity.Items.Insert(0, new ListItem("---Select---", "0"));
}


protected void ddlState_SelectedIndexChanged(object sender, EventArgs e)
{
    int StatId = Convert.ToInt32(ddlState.SelectedValue);
    string CS = ConfigurationManager.ConnectionStrings["SportsActiveConnectionString"].ConnectionString;
    using (SqlConnection con = new SqlConnection(CS))
    {
        con.Open();
        SqlCommand cmd = new SqlCommand("spCities", con);
        cmd.Parameters.AddWithValue("@StatId", StatId);
        cmd.CommandType = CommandType.StoredProcedure;
        SqlDataAdapter da = new SqlDataAdapter(cmd);
        DataSet ds = new DataSet();
        da.Fill(ds);
        ddlCity.DataSource = ds;
        ddlCity.DataTextField = "CityName";
        ddlCity.DataValueField = "CityId";
        ddlCity.DataBind();
    }
    ddlCity.Items.Insert(0, new ListItem("---Select---", "0"));
}

 ddlState.SelectedIndex = ddlState.Items.IndexOf(ddlState.Items.FindByText(rdr["State"].ToString()));
 ddlCity.SelectedIndex = ddlCity.Items.IndexOf(ddlCity.Items.FindByText(rdr["City"].ToString()));

abpve代码绑定的是州，而不是城市。城市下拉列表仍然显示---Select---。绑定城市后，我应该能够选择任何其他城市/州并再次更新。 任何帮助都将不胜感激

试试这个

ddlState.SelectedIndex = ddlState.Items.IndexOf(ddlState.Items.FindByText(rdr["State"].ToString()));

然后将城市值设置为隐藏值hf_city

hf_city.Value = rdr["City"].ToString();

然后关闭读卡器和连接，然后再次调用在ddlState\u SelectedIndexChanged上创建的函数

 int StatId = Convert.ToInt32(ddlState.SelectedValue);
    string CS = ConfigurationManager.ConnectionStrings["SportsActiveConnectionString"].ConnectionString;
    using (SqlConnection con = new SqlConnection(CS))
    {
        con.Open();
        SqlCommand cmd = new SqlCommand("spCities", con);
        cmd.Parameters.AddWithValue("@StatId", StatId);
        cmd.CommandType = CommandType.StoredProcedure;
        SqlDataAdapter da = new SqlDataAdapter(cmd);
        DataSet ds = new DataSet();
        da.Fill(ds);
        ddlCity.DataSource = ds;
        ddlCity.DataTextField = "CityName";
        ddlCity.DataValueField = "CityId";
        ddlCity.DataBind();
    }
    ddlCity.Items.Insert(0, new ListItem("---Select---", "0"));

 ddlCity.SelectedIndex = ddlCity.Items.IndexOf(ddlCity.Items.FindByText(hf_city.Value));

---

创建另一个绑定cityDropdownlist的方法：

protected void BindCityDropDown(int StatId)
{
    string CS = ConfigurationManager.ConnectionStrings["SportsActiveConnectionString"].ConnectionString;
    using (SqlConnection con = new SqlConnection(CS))
    {
        con.Open();
        SqlCommand cmd = new SqlCommand("spCities", con);
        cmd.Parameters.AddWithValue("@StatId", StatId);
        cmd.CommandType = CommandType.StoredProcedure;
        SqlDataAdapter da = new SqlDataAdapter(cmd);
        DataSet ds = new DataSet();
        da.Fill(ds);
        ddlCity.DataSource = ds;
        ddlCity.DataTextField = "CityName";
        ddlCity.DataValueField = "CityId";
        ddlCity.DataBind();
    }
    ddlCity.Items.Insert(0, new ListItem("---Select---", "0"));
}

调用此内部DropDownList选定索引更改：

protected void ddlState_SelectedIndexChanged(object sender, EventArgs e)
{
    int StatId = Convert.ToInt32(ddlState.SelectedValue);
    BindCityDropdown(StatId);
}

现在在“编辑”部分中，绑定citydropdownlist，然后赋值：

ddlState.SelectedIndex = ddlState.Items.IndexOf(ddlState.Items.FindByText(rdr["State"].ToString()));
int StatId = Convert.ToInt32(ddlState.SelectedValue);
BindCityDropdown(StatId);
 ddlCity.SelectedIndex = ddlCity.Items.IndexOf(ddlCity.Items.FindByText(rdr["City"].ToString()));

---

请发布绑定组合框的代码。请先绑定组合框，然后设置选定索引。为ddlcity和DDLSTATE使用不同的数据集。您是否尝试过使用此

dlState.SelectedValue=rdr[“State”]。ToString（）@Suprabhat-不，它甚至不绑定状态