How to use ExecuteScalar in Ado.Net with C#

How to use ExecuteScalar  in Ado.Net  with  C#

create database test

use test

create table McaStudent(RollNo int identity(1,1),StudentId as 'Mca' + cast(RollNo asvarchar(10)),Name nvarchar(50),Gender nvarchar(50),Course nvarchar(50),Addressnvarchar(max))

insert into McaStudent values('Somesh', 'Male','B. Tech.','Kanpur')

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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;

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

{

    protected void Page_Load(object sender, EventArgs e)

    {

         con = new SqlConnection("Data Source=kush;Initial Catalog=test;Integrated Security=True");

    }      

    SqlConnection con;

    protected void BtnSave_Click(object sender, EventArgs e)

    {

        con.Open();

       // SqlCommand cmd = new SqlCommand("insert into McaStudent (Name,Gender,Course,Address) output inserted.StudentId values ('" + txtName.Text + "','" + RbGender.SelectedValue + "','" + ddlCourse.SelectedItem.Text + "','" + txtAddress.Text + "')", con);

        SqlCommand cmd = new SqlCommand("insert into McaStudent  output inserted.StudentId values ('" + txtName.Text + "','" + RbGender.SelectedValue + "','" + ddlCourse.SelectedItem.Text + "','" + txtAddress.Text + "')", con);

       LStudentId.Text= ""+cmd.ExecuteScalar();

       con.Close();

       LMessage.Text = "Add Success fully";

 }

    protected void BtnNoRow_Click(object sender, EventArgs e)

    {

       int count=0;

      String sqlQuery = "Select COUNT(*) from McaStudent";

        SqlCommand cmd = new SqlCommand(sqlQuery, con);

        try

        {

            con.Open();

            //Since count  is intger,System.Object, a typecast is must

            count = (Int32)cmd.ExecuteScalar();

            LMessage.Text = count.ToString();

        }

        catch (Exception ex)

        {

            LMessage.Text = ex.Message;

        }

        finally

        {

            con.Close();

        }

     

    }

}