Hello dear

You can use select_IndexChangeEvent Like this...
And make sure Your Dropdownlist must have Autopostback property = true

Mark as solved if it helps you!!!

ThanK U for your immediate reply.
But the Text Box should display the corresponding name of customer once i select the cid (Customer iD) from the drop down list.
I need coding in c#.

Hi,
You might have stored the name of the customer in the database.
Just write a query to fetch the name from the table and add it to the textbox.

protected void dropdownlst_selectectchange(object s, evetntargs s)
{
string str=dropdownlist1.selecteditem.text;
string sql="select name from customer where custid="+str;
sqlcommand cmd=new sqlcommand(sql,connectionstring)
sqldatareader dr=cmd.executereader()
while(dr.read())
{
textbox1.text=dr[0].tostring();
}

}

Thank U very much praveen,
Now i have another problem that i am not able to select other cid from the drop down list.If i select another "cid" from the DDL also it is not effecting.It is always displaying the first item of the list.
How to solve this.please help me.

Hi,
May be you have not set the AutoPostBack property to true.
<aspropDownList ID="DropDownList1" runat="server" AutoPostBack="true" OnSelectedIndexChanged="dropdownlst_selectectchange">
</aspropDownList>

thank you,
regards

Hello Praveen,
I have given the property AutoPostBack to true.still it is giving only first item in the list.I did the code in page_load event.
Is it require to add the code in betwwen if(!page.IsPostBack) condition .
reply me soon
Thank U