title: How to assign the selected value of Drop down to text box
body: <p>I'm trying to assign the selected value in the drop down to text box when ever I hit a button. I'm not able to see the selected value in the <code>TextBox</code>. Can someone please let me know what am I missing?</p>
  
  <p>My code is as follows:</p>
  
  <pre><code>public partial class _Default : System.Web.UI.Page
  {
      protected void Page_Load(object sender, EventArgs e)
      {                       
  
      }
  
      protected void Button1_Click1(object sender, EventArgs e)
      {
  
          string strConn = "Initial Catalog=NavigateV6;Data Source=SVUSRYE-SQL3D1;User ID=dopis_user;Password=dopis_password;Persist Security Info=True;MultipleActiveResultSets=True";
          SqlConnection mycn = new SqlConnection(strConn);
          DataSet ds = new DataSet();
          SqlDataAdapter myda = new SqlDataAdapter("Select accountid FROM trn_account ", mycn);
          myda.Fill(ds);
          DDL.DataSource = ds;
          DDL.DataTextField = "AccountID";
          DDL.DataValueField = "AccountID";
          DDL.DataBind();
  
      }
  
  
  
      protected void DDL_SelectedIndexChanged(Object sender, EventArgs e)
      {
          var selectedValue = ((DropDownList)sender).SelectedValue;
          if (!string.IsNullOrEmpty(TextBox1.Text))
              TextBox1.Text = selectedValue;
  
      }
  }
  </code></pre>
  
  <p>ASPX:</p>
  
  <pre class="lang-xml prettyprint-override"><code>&lt;asp:DropDownList ID="DDL" runat="server" AutoPostBack="True" OnSelectedIndexChanged = " DDL_SelectedIndexChanged" &gt;
  
      &lt;/asp:DropDownList&gt;
  &amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;
      &lt;br /&gt;
      &lt;br /&gt;
      &lt;br /&gt;
      &lt;asp:Button ID="Button1" runat="server" onclick="Button1_Click1" 
          Text="sumbit" /&gt;
      &lt;asp:TextBox ID="TextBox1" runat="server"&gt;&lt;/asp:TextBox&gt;
      &lt;br /&gt;
  &lt;/asp:Content&gt;
  </code></pre>