Asp.net: Fill Country, State and City dropdownlist

In this article today I am going to explain How to populate the Country, State and City dropdownlist in asp.net

Description:

In the previous article I have explained Top 20 Sql server Interview questionswith answer on Select statement and ADO.Net entity framework CRUD functionusing store procedure in Gridview.

I want to populate the state dropdown on Country dropdown selection and city dropdown on state dropdown selection. I have created three tables.

Country:

State:

City:

Implementation:

Add a webform to project/website. drag and drop the required control from toolbox to webform.

HTML Markup:

<table>

        <tr>

            <td>Country :</td> <td>State :</td>  <td>City :</td>

        </tr>

           <tr><td></td>

            <td></td> <td></td>

        </tr>

          <tr>

            <td>

                <asp:DropDownList ID="ddlcountry" runat="server" AutoPostBack="true" ></asp:DropDownList></td>

              <td>

                <asp:DropDownList ID="ddlstate" runat="server" AutoPostBack="true"></asp:DropDownList></td>

              <td> <asp:DropDownList ID="ddlcity" runat="server"></asp:DropDownList></td>

        </tr>     

    </table>

Add the namespace

C#:

using System.Data;

using System.Data.SqlClient;

using System.Configuration;

VB:

Imports System.Data

Imports System.Data.SqlClient

Imports System.Configuration

Bind the Country dropdownlist

Write a function to bind country dropdownlist and call on page load event.

C#:

SqlConnection con = new SqlConnection(ConfigurationManager.ConnectionStrings["connection"].ToString());

protected void Page_Load(object sender, EventArgs e)

    {

        if(!IsPostBack)

        {

            FillCountry();

            ddlstate.Items.Insert(0, new ListItem("---Select---", "0"));

            ddlcity.Items.Insert(0, new ListItem("---Select---", "0"));

        }      

    }

    public void FillCountry()

    {

        SqlDataAdapter adp = new SqlDataAdapter("Select * from Tb_Country", con);

        DataTable dt = new DataTable();

        adp.Fill(dt);

        if(dt.Rows.Count>0)

        {

            ddlcountry.DataSource = dt;

            ddlcountry.DataTextField = "CountryName";

            ddlcountry.DataValueField = "ID";

            ddlcountry.DataBind();

            ddlcountry.Items.Insert(0, new ListItem("---Select---", "0"));

        }

    }

VB:

Dim con As New SqlConnection(ConfigurationManager.ConnectionStrings("connection").ToString())

Protected Sub Page_Load(sender As Object, e As EventArgs) Handles Me.Load

        If Not IsPostBack Then

            FillCountry()

            ddlstate.Items.Insert(0, New ListItem("---Select---", "0"))

            ddlcity.Items.Insert(0, New ListItem("---Select---", "0"))

        End If

    End Sub

    Public Sub FillCountry()

        Dim adp As New SqlDataAdapter("Select * from Tb_Country", con)

        Dim dt As New DataTable()

        adp.Fill(dt)

        If dt.Rows.Count > 0 Then

            ddlcountry.DataSource = dt

            ddlcountry.DataTextField = "CountryName"

            ddlcountry.DataValueField = "ID"

            ddlcountry.DataBind()

            ddlcountry.Items.Insert(0, New ListItem("---Select---", "0"))

        End If

    End Sub

Populate the State Dropdownlist

To populate the state dropdownlist write the below given code on SelectedIndexChnaged event of Country dropdown

C#:

protected void ddlcountry_SelectedIndexChanged(object sender, EventArgs e)

    {

        SqlDataAdapter adp = new SqlDataAdapter("Select * from Tb_State where CountryId= @id", con);

        adp.SelectCommand.Parameters.AddWithValue("id",ddlcountry.SelectedValue);

        DataTable dt = new DataTable();

        adp.Fill(dt);

        if (dt.Rows.Count > 0)

        {

            ddlstate.DataSource = dt;

            ddlstate.DataTextField = "StateName";

            ddlstate.DataValueField = "Stateid";

            ddlstate.DataBind();

            ddlstate.Items.Insert(0, new ListItem("---Select---", "0"));

        }

        else

        {

            ddlcity.Items.Clear();

            ddlcity.Items.Insert(0, new ListItem("---Select---", "0"));

            ddlstate.Items.Clear();

            ddlstate.Items.Insert(0, new ListItem("---Select---", "0"));

        }

    }

VB:

   Protected Sub ddlcountry_SelectedIndexChanged(sender As Object, e As EventArgs) Handles ddlcountry.SelectedIndexChanged

        Dim adp As New SqlDataAdapter("Select * from Tb_State where CountryId= @id", con)

        adp.SelectCommand.Parameters.AddWithValue("id", ddlcountry.SelectedValue)

        Dim dt As New DataTable()

        adp.Fill(dt)

        If dt.Rows.Count > 0 Then

            ddlstate.DataSource = dt

            ddlstate.DataTextField = "StateName"

            ddlstate.DataValueField = "Stateid"

            ddlstate.DataBind()

            ddlstate.Items.Insert(0, New ListItem("---Select---", "0"))

        Else

            ddlcity.Items.Clear()

            ddlcity.Items.Insert(0, New ListItem("---Select---", "0"))

            ddlstate.Items.Clear()

            ddlstate.Items.Insert(0, New ListItem("---Select---", "0"))

        End If

    End Sub

Populate city dropdownlist

Write the below given code on State dropdownlist SelectedIndexChanged event

C#:

protected void ddlstate_SelectedIndexChanged(object sender, EventArgs e)

    {

        SqlDataAdapter adp = new SqlDataAdapter("Select * from Tb_City where StateId= @id", con);

        adp.SelectCommand.Parameters.AddWithValue("id", ddlstate.SelectedValue);

        DataTable dt = new DataTable();

        adp.Fill(dt);

        if (dt.Rows.Count > 0)

        {

            ddlcity.DataSource = dt;

            ddlcity.DataTextField = "CityName";

            ddlcity.DataValueField = "CityId";

            ddlcity.DataBind();

            ddlcity.Items.Insert(0, new ListItem("---Select---", "0"));

        }

        else

        {

            ddlcity.Items.Clear();

            ddlcity.Items.Insert(0, new ListItem("---Select---", "0"));

        }

    }

VB:

Protected Sub ddlstate_SelectedIndexChanged(sender As Object, e As EventArgs) Handles ddlstate.SelectedIndexChanged

        Dim adp As New SqlDataAdapter("Select * from Tb_City where StateId= @id", con)

        adp.SelectCommand.Parameters.AddWithValue("id", ddlstate.SelectedValue)

        Dim dt As New DataTable()

        adp.Fill(dt)

        If dt.Rows.Count > 0 Then

            ddlcity.DataSource = dt

            ddlcity.DataTextField = "CityName"

            ddlcity.DataValueField = "CityId"

            ddlcity.DataBind()

            ddlcity.Items.Insert(0, New ListItem("---Select---", "0"))

        Else

            ddlcity.Items.Clear()

            ddlcity.Items.Insert(0, New ListItem("---Select---", "0"))

        End If

    End Sub

Build and run the project.

 Result:

  In this article we have learn to how to populate Country, State and City dropdownlist  on each other selection in asp.net. I hope you enjoyed this article.