Data binding and display data in textbox

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C#

ASP.NET

SQL

server

Hello

i am binding a dropdown with Database

Country | State | District | City

Dropdown is working fine I want to show state Code in textbox and State_Code in State Table

Question Which States I select in dropdown i want to show the State_Code of that State in Textbox

What I have tried:

<div class="form-group col-md-3">
                              <label for="inputState" class="col-form-label">State</label>
                              <asp:DropDownList ID="State_Select" CssClass="form-control" runat="server" AutoPostBack="True" DataSourceID="SqlDataSource1" DataTextField="States_Name" DataValueField="States_Id"></asp:DropDownList>

                              <asp:SqlDataSource ID="SqlDataSource1" runat="server" ConnectionString="<%$ ConnectionStrings:Retail_Billing %>" SelectCommand="SELECT * FROM [States] WHERE ([Country_Id] = @Country_Id)">
                                  <SelectParameters>
                                      <asp:Parameter DefaultValue="1" Name="Country_Id" Type="Byte" />
                                  </SelectParameters>
                              </asp:SqlDataSource>

                          </div>

                          <div class="form-group col-md-3">
                              <label for="district" class="col-form-label">District</label>
                              <asp:DropDownList ID="District_Select" CssClass="form-control" runat="server" DataSourceID="SqlDataSource2" DataTextField="District_Name" DataValueField="District_Id" AutoPostBack="True"></asp:DropDownList>
                              <asp:SqlDataSource ID="SqlDataSource2" runat="server" ConnectionString="<%$ ConnectionStrings:Retail_Billing %>" SelectCommand="SELECT * FROM [District] WHERE ([States_Id] = @States_Id)">
                                  <SelectParameters>
                                      <asp:ControlParameter ControlID="State_Select" DefaultValue="0" Name="States_Id" PropertyName="SelectedValue" Type="Byte" />
                                  </SelectParameters>
                              </asp:SqlDataSource>
                          </div>
                          <div class="form-group col-md-3">
                              <label for="Location" class="col-form-label">Location</label>
                              <asp:DropDownList ID="Location_Drop" CssClass="form-control" runat="server" DataSourceID="SqlDataSource3" DataTextField="Location_Name" DataValueField="Location_Id"></asp:DropDownList>
                              <asp:SqlDataSource ID="SqlDataSource3" runat="server" ConnectionString="<%$ ConnectionStrings:Retail_Billing %>" SelectCommand="SELECT * FROM [Location] WHERE ([District_Id] = @District_Id)">
                                  <SelectParameters>
                                      <asp:ControlParameter ControlID="District_Select" DefaultValue="0" Name="District_Id" PropertyName="SelectedValue" Type="Int32" />
                                  </SelectParameters>
                              </asp:SqlDataSource>
                          </div>


                          <div class="form-group col-md-2">
                              <label for="inputZip" class="col-form-label">Zip</label>
                              <input type="text" class="form-control" placeholder="Zip" id="inputZip">
                          </div>