App setting

<configuration>

<appSettings>

<add key="ConnStr" value="Data Source=.\SQLEXPRESS;AttachDbFilename=C:\MyData\App_Data\Database.mdf;Integrated Security=True;User Instance=True"/>

</appSettings>

<connectionStrings>

<add name="ConnStr" connectionString="Data Source=.\SQLEXPRESS;AttachDbFilename=C:\MyData\App_Data\Database.mdf;Integrated Security=True;User Instance=True"/>

</connectionStrings>

</configuration>

Aspx for a 3 tire validation

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Data;

namespace test
{
    public partial class Student : System.Web.UI.Page
    {
        protected void Page_Load(object sender, EventArgs e)
        {
            if (!IsPostBack)
            {
                hdnSTDID.Value = "Add";
            }
        }

        protected void btnSave_Click(object sender, EventArgs e)
        {
            string stdName = tbxName.Text;
            DBConnection dbConnection = new DBConnection();
            if (hdnMode.Value == "Add")
            {
                string sql = "INSERT INTO Student ([Name])  VALUES ('" + stdName + "')";
                dbConnection.ExecuteQuary(sql);

                string script = "alert(\"ADDfgfh..!\");";
                ScriptManager.RegisterStartupScript(this, this.GetType(),
                              "ServerControlScript", script, true);
            }
            if (hdnMode.Value == "Edit")
            {
                int stdId = int.Parse(hdnSTDID.Value);
                string sqlEdite = "UPDATE Student  SET Name = '" + stdName + "' WHERE StdId=" + stdId;
                dbConnection.ExecuteQuary(sqlEdite);
                hdnMode.Value = "Add";
                btnSave.Text = "Add";
            }
            gvStudent.DataBind();
            tbxName.Text = "";
        }

        protected void gvStudent_RowCommand(object sender, GridViewCommandEventArgs e)
        {
            int index = Convert.ToInt32(e.CommandArgument);
            string studentId = gvStudent.Rows[index].Cells[0].Text;
            int stdID = int.Parse(studentId);
            DBConnection con = new DBConnection();

            if (e.CommandName == "Del")
            {
                string strDelete = "DELETE FROM Student  WHERE StdId=" + stdID;

                con.ExecuteQuary(strDelete);
                gvStudent.DataBind();
            }
            if (e.CommandName == "Edi")
            {
                string sqlEdite = "SELECT  StdId, Name  FROM Student WHERE StdId=" + stdID;
                DataSet ds = con.GetData(sqlEdite);
                hdnSTDID.Value = ds.Tables[0].Rows[0]["StdId"].ToString();
                tbxName.Text = ds.Tables[0].Rows[0]["Name"].ToString();
                btnSave.Text = "Edite";
                hdnMode.Value = "Edit";
            }
        }
    }
}

Wb.Cnfg

<?xml version="1.0"?>
<!--
  For more information on how to configure your ASP.NET application, please visit
  http://go.microsoft.com/fwlink/?LinkId=169433
  -->
<configuration>
    <connectionStrings>
        <!--<add name="ApplicationServices" connectionString="data source=.\SQLEXPRESS;Integrated Security=SSPI;AttachDBFilename=|DataDirectory|\aspnetdb.mdf;User Instance=true" providerName="System.Data.SqlClient"/>-->
         <add name="connectionStringa" connectionString="data source=LOCHANA-PC;initial catalog=StdMngSystem;user id=;password=;multipleactiveresultsets=True" providerName="System.Data.SqlClient"/>
   
  </connectionStrings>
    <system.web>
        <compilation debug="true" targetFramework="4.0"/>
        <authentication mode="Forms">
            <forms loginUrl="~/Account/Login.aspx" timeout="2880"/>
        </authentication>
        <membership>
            <providers>
                <clear/>
                <add name="AspNetSqlMembershipProvider" type="System.Web.Security.SqlMembershipProvider" connectionStringName="ApplicationServices" enablePasswordRetrieval="false" enablePasswordReset="true" requiresQuestionAndAnswer="false" requiresUniqueEmail="false" maxInvalidPasswordAttempts="5" minRequiredPasswordLength="6" minRequiredNonalphanumericCharacters="0" passwordAttemptWindow="10" applicationName="/"/>
            </providers>
        </membership>
        <profile>
            <providers>
                <clear/>
                <add name="AspNetSqlProfileProvider" type="System.Web.Profile.SqlProfileProvider" connectionStringName="ApplicationServices" applicationName="/"/>
            </providers>
        </profile>
        <roleManager enabled="false">
            <providers>
                <clear/>
                <add name="AspNetSqlRoleProvider" type="System.Web.Security.SqlRoleProvider" connectionStringName="ApplicationServices" applicationName="/"/>
                <add name="AspNetWindowsTokenRoleProvider" type="System.Web.Security.WindowsTokenRoleProvider" applicationName="/"/>
            </providers>
        </roleManager>
    </system.web>
    <system.webServer>
        <modules runAllManagedModulesForAllRequests="true"/>
    </system.webServer>
</configuration>

DBC

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Data.SqlClient;
using System.Web.Configuration;
using System.Data;
/// <summary>
/// Summary description for DBConnection
/// </summary>
///
namespace StdMngSystem
{
    public class DBConnection
    {

        SqlConnection connection = new SqlConnection(WebConfigurationManager.ConnectionStrings["connectionStringa"].ToString());
        SqlCommand command = null;
        SqlDataAdapter adapter = null;

        public void ExecuteQuary(string quary)
        {
            try
            {
                if (connection.State == ConnectionState.Closed)
                {
                    connection.Open();
                    command = new SqlCommand();
                }
                command.CommandText = quary;
                command.Connection = connection;
                command.ExecuteNonQuery();
                connection.Close();
            }
            catch (Exception)
            {

            }
        }
        public DataSet GetData(string quary)
        {
            if (connection.State == ConnectionState.Closed)
            {
                connection.Open();
                adapter = new SqlDataAdapter(quary, connection);
            }
            DataSet getDataSet = new DataSet();
            adapter.Fill(getDataSet);
            connection.Close();
            return getDataSet;
        }
    }
}