How to set TextBox Text when value selected from DropDown

Question

I have a database table named tblCityState with the following data:

CITY	STATE
New York	New York
Los Angeles	California
Atlanta	Georgia

on my aspx page I have a dropdown (ddCity) bound to the table (Select City from tblCityState).

When the user Selects "Los Angeles" from the DropDown, I want a textbox (tbState) to be populated with "California".

Now, I could set the value of the DropDown Item to be the State, but I want the Item value to be the City.

What is the best / easiest way to achive this with ASP.NET / C# / AJAX?

Thanks
Gary

Sandeep Shekhawat · Answer

bound a drop down list Like you give .aspx page take one dropdown and one textbox like onselectedindexchanged=ddcity_SelectedIndexChanged AutoPostBack=true> .aspx.cs page Write code like: using System; using System.Collections.Generic; using System.Linq; using System.Web; using System.Web.UI; using System.Web.UI.WebControls; using System.Data.SqlClient; using System.Data; namespace ResultSystem.Admin { public partial class home : System.Web.UI.Page { protected void Page_Load(object sender EventArgs e) { if(!Page.IsPostBack) { FillDropdown(); } } //Filldrop down void FillDropdown() { SqlConnection con=new SqlConnection(@Data Source=SANPEEP-PC\SANDEEP; database=Result; user=sa; password=123);//here your connection string; con.Open(); SqlCommand cmd=new SqlCommand(select * from tblcitystatecon); SqlDataAdapter dap=new SqlDataAdapter(cmd); DataSet ds=new DataSet(); dap.Fill(ds); ddcity.DataSource=ds; ddcity.DataTextField=CITY;//Database table filed name for display in dropdown ddcity.DataValueField=STATE;//display in textbox when select dropdown field ddcity.DataBind(); } protected void ddcity_SelectedIndexChanged(object sender EventArgs e) { txtcity.Text=ddcity.SelectedValue.ToString();// get value form dropdown } } } OUTPUT

Pradeep Chandraker · Answer

You can have the datatable stored in ViewState. And OnSelectedIndexChanged even you can select state from datatable based on cityId.

Suthish Nair · Answer

Why don't try CascadingDropDown control. Otherwise.. SELECT City_Name ' ddlText ' City_ID + '~' + State_Name + '~' + Population ' ddlID ' FROM tblCITY Later you can split the value and fetch the records..

Gary King · Answer

Ok so my form is entirely within an update panel already. I still dont think my question has been answered so let me try a different approach.... Lets assume that the databind for the dropdown is something like this: SELECT City_ID City_Name State_Name Population FROM tblCITY Is it possible using ASP.NET and/or AJAX to make use of more than 2 columns (ID & Text)? If I select the City in the dropdown can I then use the State_Name Popuulation or any of the columns to populate a Textbox? The Dropdown ID and Text will be the City_Name. Sure this can be achieved with an event handler that would query the table again based on which City was selected but I am asking if there is any other / simpler way.

Sandeep Shekhawat · Answer

Sorry i could not understand ur problem. But i suggest u if ur using AJAX unabled website then use Update panel and inner this dropdown or u can use dropdown or New York Los Angeles Atlanta for this code use JavaScript onchange() Event

Gary King · Answer

Thanks for the suggested code but I think you missed the main point of my question.... I want the dropdown text and value to be the City - Los Angeles and therefore I cannot simply set the State text box value to be the City SelectedValue. In other words the resultant HTML for the dropdown would be something like: New York Los Angeles Atlanta This may not make much sense - especially as the example is somewhat of a simplified version of what I want to achieve. I could just write a C# event handler for the dropdown that would basically query the database using the dropdown value as a filter criteria and then set the textbox value to be the result of the query. BUT  I was wondering if there is a better / easier way to do this - especially considering that the website is AJAX enabled.