Asp. NET program to achieve a three-color alternating drop-down list box

Asp.net| Program | dropdown | The drop-down list shows a drop-down box with alternating three colors, as shown in the following illustration.


  


  


Implementation method:


1. Use the System.Web.UI.HtmlControls control to run it as a server control.


2. Binds the data to this select control in the background.


3. Then call a write-yourself function to specify the color for its items.


Implementation code (main implementation part):


Front Desk (WebForm1.aspx):


<select id= "Select1" style= "width:300px" name= "Select1" runat= "Server" >


<option selected></option>


</SELECT>


Backstage (WebForm1.aspx.cs):


private void Page_Load (object sender, System.EventArgs e)


  {


if (! IsPostBack)


  {


SqlConnection cnn = new SqlConnection ();


CNN. ConnectionString = "Data source=localhost;initial catalog=northwind;password=;"


+ "Persist security info=true;user id=sa;workstation id=apj062;packet size=4096";


string sqlstr = "Select Top CustomerID, CompanyName from Customers";


CNN. Open ();


SqlDataAdapter ad = new SqlDataAdapter (SQLSTR,CNN);


DataTable dt = new DataTable ();


AD. Fill (DT);


select1.datasource = DT;


Select1.datatextfield = "CompanyName";


Select1.datavaluefield = "CustomerID";


Select1.databind ();


Bindselectcolor (SELECT1);


  }


  }


//Add a style to a project for a select control


void Bindselectcolor (HtmlSelect Select)


  {


int num = 0;


string stylestring = "";


for (int i = 0; i < SELECT. Items.Count; i + +)


  {


num = i% 3;


switch (num)


  {


Case 0:


  {


stylestring = "COLOR: #000099; Background-color: #F4FAFF ";


break;


  }


Case 1:


  {


stylestring = "COLOR: #990000; Background-color: #FFFAFB ";


break;


  }


Case 2:


  {


stylestring = "COLOR: #009900; Background-color: #F4FFFA ";


break;


  }


  }


Select. Items[i]. Attributes.Add ("style", stylestring);


  }


  }