C#, read data from Excel (*.xls) file

var file = Server.MapPath("file.xls");
var cs = string.Format("Provider=Microsoft.Jet.OLEDB.4.0;Data Source={0};Extended Properties=Excel 8.0;", file);

using(var conn = new OleDbConnection(cs))
{
  using(var cmd = new OleDbCommand("SELECT * FROM [Sheet1$]", conn))
  {
    using(var adapter = new OleDbDataAdapter(cmd))
    {
      var table = new DataTable();

      adapter.Fill(table);

      grid.DataSource = table;
      grid.DataBind();
    }
  }
}