using System;
using System.Windows.Forms;
using System.Data;
using System.Data.SqlClient;
using Excel = Microsoft.Office.Interop.Excel; 

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

        private void button1_Click(object sender, EventArgs e)
        {
            SqlConnection cnn ;
            string connectionString = null;
            string sql = null;

            connectionString = "data source=servername;initial catalog=databasename;user id=username;password=password;";
            cnn = new SqlConnection(connectionString);
            cnn.Open();
            sql = "SELECT * FROM Product";
            SqlDataAdapter dscmd = new SqlDataAdapter(sql, cnn);
            DataSet ds = new DataSet();
            dscmd.Fill(ds);

            dataGridView1.DataSource = ds.Tables[0];
        }

        private void button2_Click(object sender, EventArgs e)
        {
            Excel.Application xlApp ;
            Excel.Workbook xlWorkBook ;
            Excel.Worksheet xlWorkSheet ;
            object misValue = System.Reflection.Missing.Value;

            xlApp = new Excel.ApplicationClass();
            xlWorkBook = xlApp.Workbooks.Add(misValue);
            xlWorkSheet = (Excel.Worksheet)xlWorkBook.Worksheets.get_Item(1);
            int i = 0;
            int j = 0; 

            for (i = 0; i <= dataGridView1.RowCount  - 1; i++)
            {
                for (j = 0; j <= dataGridView1.ColumnCount  - 1; j++)
                {
                    DataGridViewCell cell = dataGridView1[j, i];
                    xlWorkSheet.Cells[i + 1, j + 1] = cell.Value;
                }
            }

            xlWorkBook.SaveAs("csharp.net-informations.xls", Excel.XlFileFormat.xlWorkbookNormal, misValue, misValue, misValue, misValue, Excel.XlSaveAsAccessMode.xlExclusive, misValue, misValue, misValue, misValue, misValue);
            xlWorkBook.Close(true, misValue, misValue);
            xlApp.Quit();

            releaseObject(xlWorkSheet);
            releaseObject(xlWorkBook);
            releaseObject(xlApp);

            MessageBox.Show("Excel file created , you can find the file c:\\csharp.net-informations.xls");
        }

        private void releaseObject(object obj)
        {
            try
            {
                System.Runtime.InteropServices.Marshal.ReleaseComObject(obj);
                obj = null;
            }
            catch (Exception ex)
            {
                obj = null;
                MessageBox.Show("Exception Occured while releasing object " + ex.ToString());
            }
            finally
            {
                GC.Collect();
            }
        }

    }
}