Bind Dropdown from data table in asp.net

   Step 1 -Creating Table in SQL Server Database

create a table named MstUser with the columns id, name, country and city. Set the identity property=true for id.

Step 2- insert data into ‘MstUser’ Table

Like this:-

Step 3 -Now You have to Create a WebApplication

1.               Go to Visual Studio 2015
2.          New Project ->Web->Asp.net Web Application->-Web Forms>Click Ok

Step 4-Now Add Web Page

1. ·         Go to the Solution Explorer
2. ·         Right –Click on the Project Name
3. ·         Select  ’add New Item’ option
4. ·         Add new  Web Form from Items and give Name
5. ·         Click OK

Step 5-Design the page and place the required control on it.

Now drag and drop one DropDownList control, One Button and  one GridView control on the form from toolbox . Like given bellow .

Step 6-Now add the following namespaces:

1.  using System.Data.SqlClient;
2.   using System.Data;

Step 7-Now write the connection string to connect to the database:

string str = "Data Source=RND-PCTPX04\\SQLEXPRESS_2014;Initial Catalog=DemoDb;Integrated Security=True";

Step 8-Now bind the DropDownList with the database table.

            Go to cs file of web form and write this code on page load event

protected void Page_Load(object sender, EventArgs e)     {         SqlConnection con = new SqlConnection(str);         string com = "Select * from MstUser";         SqlDataAdapter adpt = new SqlDataAdapter(com, con);         DataTable dt = new DataTable();         adpt.Fill(dt);         DropDownList1.DataSource = dt;         DropDownList1.DataBind();         DropDownList1.DataTextField = "UserName";         DropDownList1.DataValueField = "ID";         DropDownList1.DataBind();     }

Step 9-Now double-click on the Button control and add the following code:

SqlConnection con = new SqlConnection(str);           SqlCommand cmd = new SqlCommand("select * from MstUser where id = '" + Drop    DownList1.SelectedValue + "'", con);           SqlDataAdapter Adpt = new SqlDataAdapter(cmd);           DataTable dt = new DataTable();           Adpt.Fill(dt);           GridView1.DataSource = dt;           GridView1.DataBind();           Label1.Text = "record found";

Step 10-Code-behind file

To display data in The GridViw use a DataAdapter object to retrieve the data from the database and place that data into a table.

using System; using System.Collections.Generic; using System.Linq; using System.Web; using System.Web.UI; using System.Web.UI.WebControls; using System.Data.SqlClient; using System.Data; namespace Demo {     public partial class ShowDropdown : System.Web.UI.Page     {         string str = "Data Source=RND-PCTPX04\\SQLEXPRESS_2014;Initial Catalog=DemoDb;Integrated Security=True";         protected void Page_Load(object sender, EventArgs e)         {             SqlConnection con = new SqlConnection(str);             string com = "Select * from MstUser";             SqlDataAdapter adpt = new SqlDataAdapter(com, con);             DataTable dt = new DataTable();             adpt.Fill(dt);             DropDownList1.DataSource = dt;             DropDownList1.DataBind();             DropDownList1.DataTextField = "UserName";             DropDownList1.DataValueField = "ID";             DropDownList1.DataBind();         }         protected void Button1_Click1(object sender, EventArgs e)         {             SqlConnection con = new SqlConnection(str);             SqlCommand cmd = new SqlCommand("select * from MstUser where id = '" + DropDownList1.SelectedValue + "'", con);             SqlDataAdapter Adpt = new SqlDataAdapter(cmd);             DataTable dt = new DataTable();             Adpt.Fill(dt);             GridView1.DataSource = dt;             GridView1.DataBind();             Label1.Text = "record found";         }     } }

Step 11-Now run the application  

You will get desired result means you dropdown list load with data from database

Step 12-Now select the User name from DropDownList control and click on the Button to se all details of user .