State District City Dropdownlist Asp.net c#

State District City Dropdownlist Asp.net c# 

State District City Dropdownlist Asp.net c#:
Today I'm discussing about how to show State District and City Dropdownlist according to previous selected values.In most of the projects we need to show some data or record according to selected values of dropdownlist.So,I have added this part also to complete the project.

Step 1: Create State,District,City and SampleData table in mssql.
Step 2:Add three dropdownlist State,District,City and one drigview to show records.
Step 3:Bind data dynamically in code behind.

Sql Script to create State, District, City and SampleData table in mssql:

CREATE TABLE State (
  ID int NOT NULL identity(1,1) PRIMARY KEY,
  State_Name varchar(500) NOT NULL
);

CREATE TABLE District(
  ID int NOT NULL identity(1,1) PRIMARY KEY,
  State_ID int NOT NULL,
  District_Name varchar(500) NOT NULL
);

CREATE TABLE City (
  ID int NOT NULL identity(1,1) PRIMARY KEY,
  District_ID int NOT NULL,
  City_Name varchar(500) NOT NULL
);

CREATE TABLE SampleData( 
ID int NOT NULL identity(1,1) PRIMARY KEY,
City_Id int NOT NULL,
SampleField varchar(500) NOT NULL,
);

I have added few sample data in table:

INSERT INTO State( State_Name) VALUES ('Sample State Name 1');

INSERT INTO District( State_Id, District_Name) VALUES ('1','District 1');
INSERT INTO District( State_Id, District_Name) VALUES ('1','District 2');

INSERT INTO City(District_Id, City_Name) VALUES ('1','City 1 District 1');
INSERT INTO City(District_Id, City_Name) VALUES ('1','City 2 District 1');
INSERT INTO City(District_Id, City_Name) VALUES ('2','City 1 District 2');
INSERT INTO City(District_Id, City_Name) VALUES ('2','City 2 District 2');


INSERT INTO SampleData(City_Id, SampleField) VALUES ('1','Sample Field for City 1 of District 1');

Add the following namespaces in Asp.net project:

using System.Data.SqlClient;
using System.Data;
using System.Configuration;

Now add connection string.To prevent Sql injection add connection string in web.config file.

Complete code for fetch record according to state district and city:

public partial class _Default : System.Web.UI.Page 
{
   string DataConnection = ConfigurationManager.ConnectionStrings["DataConnection"].ConnectionString;
    protected void Page_Load(object sender, EventArgs e)
    {

        if (!IsPostBack)
        {
            BindStateDropDownList();
        }

    }
   
    protected void BindStateDropDownList()
    {
        SqlConnection con = new SqlConnection(DataConnection);
        con.Open();
        SqlCommand cmd = new SqlCommand("select * from State", con);
        SqlDataAdapter da = new SqlDataAdapter(cmd);
        DataSet ds = new DataSet();
        da.Fill(ds);
        con.Close();
        ddlState.DataSource = ds;
        ddlState.DataTextField = "State_Name";
        ddlState.DataValueField = "ID";
        ddlState.DataBind();
        ddlState.Items.Insert(0, new ListItem("Select Your State", "0"));
        ddlDistrict.Items.Insert(0, new ListItem("Select Your District", "0"));
        ddlCity.Items.Insert(0, new ListItem("Select Your City", "0"));

    }
 
    protected void ddlState_SelectedIndexChanged(object sender, EventArgs e)
    {
        int StateID = Convert.ToInt32(ddlState.SelectedValue);
        SqlConnection con = new SqlConnection(DataConnection);
        con.Open();
        SqlCommand cmd = new SqlCommand("select * from District where State_ID=" + StateID, con);
        SqlDataAdapter da = new SqlDataAdapter(cmd);
        DataSet ds = new DataSet();
        da.Fill(ds);
        con.Close();
        ddlDistrict.DataSource = ds;
        ddlDistrict.DataTextField = "district_Name";
        ddlDistrict.DataValueField = "ID";
        ddlDistrict.DataBind();
        ddlDistrict.Items.Insert(0, new ListItem("Select Your District", "0"));
        if (ddlDistrict.SelectedValue == "0")
        {
            ddlCity.Items.Clear();
            ddlCity.Items.Insert(0, new ListItem("Select Your City", "0"));
        }

    }
   
    protected void ddlDistrict_SelectedIndexChanged(object sender, EventArgs e)
    {
        int DistrictID = Convert.ToInt32(ddlDistrict.SelectedValue);
        SqlConnection con = new SqlConnection(DataConnection);
        con.Open();
        SqlCommand cmd = new SqlCommand("select * from City where District_ID=" + DistrictID, con);
        SqlDataAdapter da = new SqlDataAdapter(cmd);
        DataSet ds = new DataSet();
        da.Fill(ds);
        con.Close();
        ddlCity.DataSource = ds;
        ddlCity.DataTextField = "City_Name";
        ddlCity.DataValueField = "ID";
        ddlCity.DataBind();
        ddlCity.Items.Insert(0, new ListItem("Select Your City", "0"));
    }

    protected void ddlCity_SelectedIndexChanged(object sender, EventArgs e)
    {
        int CityID = Convert.ToInt32(ddlCity.SelectedValue);
        SqlConnection con = new SqlConnection(DataConnection);
        con.Open();
        SqlCommand cmd = new SqlCommand("select * from SampleData where City_ID=" + CityID, con);
        SqlDataAdapter da1 = new SqlDataAdapter(cmd);
        DataTable dt1 = new DataTable();
        da1.Fill(dt1);
        grddetails.DataSource = dt1;
        grddetails.DataBind();
 con.Close();

        
    }
}