In this blog we will know how to Display related items in gridview when dropdownlist is selected.

<%@ Page Language="C#" AutoEventWireup="true" CodeBehind="Default.aspx.cs" Inherits="Dropdownlist_gridview._Default" %>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

<html xmlns="http://www.w3.org/1999/xhtml" >

<head runat="server">

<title>Untitled Page</title>

</head>

<body>

<form id="form1" runat="server">

<div>

<asp:DropDownList ID="DropDownList1" runat="server" AutoPostBack="True"

onselectedindexchanged="DropDownList1_SelectedIndexChanged">

</asp:DropDownList><br />

<asp:GridView ID="GridView1" runat="server">

</asp:GridView>

</div>

</form>

</body>

</html>

using System;

using System.Collections;

using System.Configuration;

using System.Data;

using System.Linq;

using System.Web;

using System.Web.Security;

using System.Web.UI;

using System.Web.UI.HtmlControls;

using System.Web.UI.WebControls;

using System.Web.UI.WebControls.WebParts;

using System.Xml.Linq;

using System.Data.SqlClient;

namespace Dropdownlist_gridview

{

public partial class _Default : System.Web.UI.Page

{

string strConnString = ConfigurationManager.ConnectionStrings["ConnectionString"].ConnectionString;

SqlCommand com;

SqlDataAdapter sqlda;

DataSet ds;

string str;

protected void Page_Load(object sender, EventArgs e)

{

SqlConnection con = new SqlConnection(strConnString);

if (!IsPostBack)

{

DropDownList1.Items.Add("Choose Id");

con.Open();

str = "select * from employee";

com = new SqlCommand(str, con);

SqlDataReader reader = com.ExecuteReader();

while (reader.Read())

{

DropDownList1.Items.Add(reader["empid"].ToString());

}

reader.Close();

con.Close();

}

}

protected void DropDownList1_SelectedIndexChanged(object sender, EventArgs e)

{

SqlConnection con = new SqlConnection(strConnString);

con.Open();

str = "select * from employee where empid='" + DropDownList1.SelectedItem.Text + "'";

com = new SqlCommand(str, con);

sqlda = new SqlDataAdapter(str,con);

ds = new DataSet();

sqlda.Fill(ds, "employee");

GridView1.DataMember = "employee";

GridView1.DataSource = ds;

GridView1.DataBind();

con.Close();

}

}

}