Code Behind Code is as follows:-

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

public partial class Default2 : System.Web.UI.Page
{
    SqlConnection con = new SqlConnection("server=.;database=db;uid=sa;pwd=wintellect");
    SqlDataAdapter da;
    SqlCommand cmd;
    DataSet ds= new DataSet();
    SqlDataReader dr;
    protected void Page_Load(object sender, EventArgs e)
    {
      if (!IsPostBack)
      {
       show();
      }
    }
    public void show()
    {
      da = new SqlDataAdapter("select * from employee", con);
      da.Fill(ds);
      GridView1.DataSource = ds;
      GridView1.DataBind();
     }
}

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Code for Inserting Records:-

protected void Button1_Click(object sender, EventArgs e)
{
    string str = "insert into employee
values(@emp_id,@emp_name,@emp_salary)";
    cmd = new SqlCommand(str, con);
    cmd.Parameters.AddWithValue("@emp_id", TextBox1.Text);
    cmd.Parameters.AddWithValue("@emp_name", TextBox2.Text);
    cmd.Parameters.AddWithValue("@emp_salary", TextBox3.Text);
    con.Open();
    cmd.ExecuteNonQuery();
    con.Close();
    show();
    Response.Write("Record Inserted");
}

Code for Updating Records:-

protected void Button2_Click(object sender, EventArgs e)
{
    string str = "update employee set
emp_name=@emp_name,emp_salary=@emp_salary where emp_id=@emp_id";
    cmd = new SqlCommand(str, con);
    cmd.Parameters.AddWithValue("@emp_id", TextBox1.Text);
    cmd.Parameters.AddWithValue("@emp_name", TextBox2.Text);
    cmd.Parameters.AddWithValue("@emp_salary", TextBox3.Text);
    con.Open();
    dr = cmd.ExecuteReader();
    con.Close();
    show();
    Response.Write("Record Updated");

}

Code for Deleting Records:-

protected void Button3_Click(object sender, EventArgs e)
{
    string str = "delete from employee where
emp_id=@emp_id";
    cmd = new SqlCommand(str, con);
    cmd.Parameters.AddWithValue("@emp_id", TextBox1.Text);
    con.Open();
    dr = cmd.ExecuteReader();
    con.Close();
    show();
    Response.Write("Record Deleted");

}

 Hope, this article helps for beginners. J