using System;
using System.Drawing;
using System.Windows.Forms;
using Excel = Microsoft.Office.Interop.Excel; 

namespace WindowsApplication1
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void button1_Click(object sender, EventArgs e)
        {
            try
            {
                System.Data.OleDb.OleDbConnection MyConnection ;
                System.Data.OleDb.OleDbCommand myCommand = new System.Data.OleDb.OleDbCommand();
                string sql = null;
                MyConnection = new System.Data.OleDb.OleDbConnection("provider=Microsoft.Jet.OLEDB.4.0;Data Source='c:\\csharp.net-informations.xls';Extended Properties=Excel 8.0;");
                MyConnection.Open();
                myCommand.Connection = MyConnection;
                sql = "Update [Sheet1$] set name = 'New Name' where id=1";
                myCommand.CommandText = sql;
                myCommand.ExecuteNonQuery();
                MyConnection.Close();
            }
            catch (Exception ex)
            {
                MessageBox.Show (ex.ToString());
            }
        }
   }
}