Read excel file in C#

In Web Forms

using System;

using System.Configuration;

using System.Data;

using System.Linq;

using System.Web;

using System.Web.Security;

using System.Web.UI;

using System.Web.UI.HtmlControls;

using System.Web.UI.WebControls;

using System.Web.UI.WebControls.WebParts;

using System.Xml.Linq;

using System.Data.OleDb;

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

{

    protected void Page_Load(object sender, EventArgs e)

    {

    }

    protected void Button1_Click(object sender, EventArgs e)

    {

        string target = Server.MapPath("~/Upload");

        if (FileUpload1.HasFile)

        {

            FileUpload1.SaveAs(System.IO.Path.Combine(target, FileUpload1.FileName));

            string connectionString = String.Format(@"Provider=Microsoft.Jet.OLEDB.4.0;Data Source={0};Extended Properties=""Excel 8.0;HDR=YES;IMEX=1;""", target + "\\" + FileUpload1.FileName);

            string query = String.Format("select * from [{0}$]", "Sheet1");

            OleDbDataAdapter dataAdapter = new OleDbDataAdapter(query, connectionString);

            DataSet dataSet = new DataSet();

            dataAdapter.Fill(dataSet);

            GridView1.DataSource = dataSet.Tables[0];

            GridView1.DataBind();

        }       

    }

}

In Windows Forms

using System;

using System.Collections.Generic;

using System.ComponentModel;

using System.Data;

using System.Drawing;

using System.Linq;

using System.Text;

using System.Windows.Forms;

using System.Data.OleDb;

namespace Read_Excel_Windows_Forms

{

    public partial class Form1 : Form

    {

        public Form1()

        {

            InitializeComponent();

            InitializeOpenFileDialog();

        }

        private void InitializeOpenFileDialog()

        {           

            this.openFileDialog1.Title = "Select an excel file";

        }

        private void button1_Click(object sender, EventArgs e)

        {

            DialogResult dr = this.openFileDialog1.ShowDialog();

            if (dr == System.Windows.Forms.DialogResult.OK)

            {

                string connectionString = String.Format(@"Provider=Microsoft.Jet.OLEDB.4.0;Data Source={0};Extended Properties=""Excel 8.0;HDR=YES;IMEX=1;""", openFileDialog1.FileName);

                string query = String.Format("select * from [{0}$]", "Sheet1");

                OleDbDataAdapter dataAdapter = new OleDbDataAdapter(query, connectionString);

                DataSet dataSet = new DataSet();

                dataAdapter.Fill(dataSet);

                dataGridView1.DataSource = dataSet.Tables[0];                

            }

        }

    }

}