Select All option for two or more drop-downs

Question

I have two drop-down lists in which one is “Status” and the other is “Cluster”. Both of these drop-downs are relational. For example, if I select Kerala in State, Cluster will populate important cities and dist. like Pathnamthitta, calicut, palakad, etc.

So, I want, I want to give the option "Select All" in State and Cluster ddl.

I went through:

How to select all entries in DropDownList

http://www.w3schools.com/aspnet/control_dropdownlist.asp

http://forums.asp.net/t/1221977.aspx?Adding+a+Select+all+option+to+a+drop+down+list

But none of them worked for me. I can be able to select everything in a state, but not get cluster values ​​populated on another ddl.

This is my code for the "State" ddl:

protected void Page_Load(object sender, EventArgs e)
{
if (!IsPostBack)
{
DataSet3TableAdapters.tbl_energy_reportTableAdapter state;
state = new DataSet3TableAdapters.tbl_energy_reportTableAdapter();
DataTable dt = new DataTable();
dt = state.GetDataByStateInnerJoin();
DropDownList1.DataSource = dt;
DropDownList1.DataTextField = "state1";
DropDownList1.DataValueField = "state1";
DropDownList1.DataBind();                
DropDownList1.Items.Insert(0, new System.Web.UI.WebControls.ListItem("--Select State--", "0"));
DropDownList2.Items.Insert(0, new System.Web.UI.WebControls.ListItem("--Select Cluster--", "0"));
}
}

""

protected void DropDownList1_SelectedIndexChanged(object sender, EventArgs e)
{

DataSet3TableAdapters.tbl_energy_reportTableAdapter state;
state = new DataSet3TableAdapters.tbl_energy_reportTableAdapter();
DataTable dt = new DataTable();
dt = state.GetDataByClusterInnerJoin(DropDownList1.SelectedValue);
DropDownList2.DataSource = dt;
DropDownList2.DataTextField = "cluster";
DropDownList2.DataValueField = "cluster";
DropDownList2.DataBind();

}

ddl:

SELECT DISTINCT tbl_site_details.state1
FROM            tbl_site_details INNER JOIN
                         tbl_energy_report ON tbl_energy_report.Site_ID = tbl_site_details.site_id

ddl:

SELECT        tbl_site_details.cluster
FROM            tbl_site_details INNER JOIN
                         tbl_energy_report ON tbl_energy_report.Site_ID = tbl_site_details.site_id
WHERE        (tbl_site_details.state1 = @state1)

Answer 1

, ddl2 dt ddl1_selectedindexchanged.

"DropDownList2.Items.Insert" _

protected void Page_Load(object sender, EventArgs e)
{
if (!IsPostBack)
{
DataSet3TableAdapters.tbl_energy_reportTableAdapter state;
state = new DataSet3TableAdapters.tbl_energy_reportTableAdapter();
DataTable dt = new DataTable();
dt = state.GetDataByStateInnerJoin();
DropDownList1.DataSource = dt;
DropDownList1.DataTextField = "state1";
DropDownList1.DataValueField = "state1";
DropDownList1.DataBind();                
DropDownList1.Items.Insert(0, new System.Web.UI.WebControls.ListItem("--Select State--", "0"));
//COMMENT THIS LINE
//DropDownList2.Items.Insert(0, new System.Web.UI.WebControls.ListItem("--Select Cluster--", "0"));
}
}

dropdownlist1_selectedindexchanged .

protected void DropDownList1_SelectedIndexChanged(object sender, EventArgs e)
{

DataSet3TableAdapters.tbl_energy_reportTableAdapter state;
state = new DataSet3TableAdapters.tbl_energy_reportTableAdapter();
DataTable dt = new DataTable();
dt = state.GetDataByClusterInnerJoin(DropDownList1.SelectedValue);
DropDownList2.DataSource = dt;
DropDownList2.DataTextField = "cluster";
DropDownList2.DataValueField = "cluster";
DropDownList2.DataBind();

//put it here
DropDownList2.Items.Insert(0, new System.Web.UI.WebControls.ListItem("--Select Cluster--", "0"));
}

Answer 2

Ajax . , , . json.