DopDownList

Dropdown List is one of the standard controls which we are using in a wide range.

This control restricts the user to select only one item.

Sample Code to do Operations with DopDownList

<asp:DropDownList ID="DropDownList1" runat="server">

</asp:DropDownList>

Code to Bind the Draopdown List with Data Source

DataSet ds = new DataSet();

ds = GetData();

//For binding data in Draopdown you need to specify which column is

//to displayed Draopdown and which column is the value filed.

//Otherwise Draopdown doesn't is in ambigious to show which column

DropDownList1.DataSource = ds;

DropDownList1.DataTextField = "ItemName";

DropDownList1.DataValueField = "ItemID";

DropDownList1.DataBind();

//Code to Add Items into Draopdown List

//By default it adds all list iltems from bottom level

string[] Weeks = { "Mon", "Tue", "Wed", "Thu", "Fri", "Sat", "Sun" };

for (int i = 0; i < Weeks.Length; i++)

{

    ListItem li = new ListItem(Weeks[i], (i + 1).ToString());

    DropDownList1.Items.Add(li);

}

//Code to Insert Items into Draopdown List

//if you want to insert a list item into Draopdown

//you need specify the location

DropDownList1.Items.Insert(0,

    new ListItem("--Select One--", "-1"));

//Code to access the Draopdown list values

foreach (ListItem li in DropDownList1.Items)

{

    if (Convert.ToInt32(li.Value) > 10)

    {

        Label1.Text += li.Text + "<br/>";

    }

}

//Code to clear the selection

DropDownList1.ClearSelection();

//Code to remove all items from DropDownList

DropDownList1.Items.Clear();

//Code to make selected perticular item

//DropDownList deosn't supports muliple selection at a time,

//so for better coding Clear the Selection of items.

//Before goint to make seletion an item check weather

//that item is exist ot not.

if (DropDownList1.Items.Contains(DropDownList1.Items.FindByValue("11")))

{

    DropDownList1.ClearSelection();

    DropDownList1.Items.FindByValue("11").Selected = true;

}