Creating & Retrieving records from M.S.Access-2007 using Oledb in C#.net

using System;
using System.Data;
using System.Windows.Forms;
using System.Data.OleDb;
using Microsoft.VisualBasic;

namespace prash_access07
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        OleDbConnection con;
        OleDbCommand cmd;
        OleDbDataAdapter adapter;
        DataSet ds;
        int rno;
        private void Form1_Load(object sender, EventArgs e)
        {
            con = new OleDbConnection(@"provider=Microsoft.ace.Oledb.12.0;data source=E:\prash\stud.accdb;Persist Security Info=False");//stud.accdb->access07 filename
            loaddata();
            showdata();
        }
        void loaddata()
        {
            adapter = new OleDbDataAdapter("select * from student", con);
            ds = new DataSet();//student-> table name in stud.accdb file
            adapter.Fill(ds, "student");
            ds.Tables[0].Constraints.Add("pk_sno", ds.Tables[0].Columns[0], true);//creating primary key for Tables[0] in dataset
            dataGridView1.DataSource = ds.Tables[0];
        }
        void showdata()
        {
            textBox1.Text = ds.Tables[0].Rows[rno][0].ToString();
            textBox2.Text = ds.Tables[0].Rows[rno][1].ToString();
            textBox3.Text = ds.Tables[0].Rows[rno][2].ToString();
        }
        private void btnFirst_Click(object sender, EventArgs e)
        {
            if (ds.Tables[0].Rows.Count > 0)
            {
                rno = 0;
                showdata();
            }
            else
                MessageBox.Show("no records");
        } 
        private void btnPrevious_Click(object sender, EventArgs e)
        {
            if (ds.Tables[0].Rows.Count > 0)
            {
                if (rno > 0)
                {
                    rno--;
                    showdata();
                }
                else
                    MessageBox.Show("First Record");
            }
            else
                MessageBox.Show("no records");
        }

        private void btnNext_Click(object sender, EventArgs e)
        {
            if (ds.Tables[0].Rows.Count > 0)
            {
                if (rno < ds.Tables[0].Rows.Count - 1)
                {
                    rno++;
                    showdata();
                }
                else
                    MessageBox.Show("Last Record");
 
            }
            else
                MessageBox.Show("no records");
        }

        private void btnLast_Click(object sender, EventArgs e)
        {
            if (ds.Tables[0].Rows.Count > 0)
            {
                rno = ds.Tables[0].Rows.Count - 1;
                showdata();
            }
            else
                MessageBox.Show("no records");
        }
        private void btnInsert_Click(object sender, EventArgs e)
        {
            cmd = new OleDbCommand("insert into student values(" + textBox1.Text + ",' " + textBox2.Text + " ',' " + textBox3.Text + " ')", con);
            con.Open();
            int n = cmd.ExecuteNonQuery();
            con.Close();

            if (n > 0)
            {
                MessageBox.Show("record inserted");
                loaddata();
            }
            else
                MessageBox.Show("insertion failed");
        }
        private void btnSearch_Click(object sender, EventArgs e)
        {
            int n = Convert.ToInt32(Interaction.InputBox("Enter sno:", "Search", "20", 200, 200));
            DataRow drow = ds.Tables[0].Rows.Find(n);
            if (drow != null)
            {
                rno = ds.Tables[0].Rows.IndexOf(drow);
                textBox1.Text = drow[0].ToString();
                textBox2.Text = drow[1].ToString();
                textBox3.Text = drow[2].ToString();
            }
            else
                MessageBox.Show("Record not found");
        }
        private void btnUpdate_Click(object sender, EventArgs e)
        {
            cmd = new OleDbCommand("update student set sname='" + textBox2.Text + "',course='" + textBox3.Text + "' where sno=" + textBox1.Text, con);
            con.Open();
            int n = cmd.ExecuteNonQuery();
            con.Close();
            if (n > 0)
            {
                MessageBox.Show("Record Updated");
                loaddata();
            }
            else
                MessageBox.Show("Update failed");
        }
        private void btnDelete_Click(object sender, EventArgs e)
        {
            cmd = new OleDbCommand("delete from student where sno=" + textBox1.Text, con);
            con.Open();
            int n = cmd.ExecuteNonQuery();
            con.Close();
            if (n > 0)
            {
                MessageBox.Show("Record Deleted");
                loaddata();
            }

            else
                MessageBox.Show("Deletion failed");
        }
        private void btnClear_Click(object sender, EventArgs e)
        {
            textBox1.Text = textBox2.Text = textBox3.Text = "";
        }

        private void btnExit_Click(object sender, EventArgs e)
        {
            this.Close();
        }

    }
}