Import Excel file

        private void btnImportFromExcel_Click(object sender, EventArgs e)        {            try            {                string fileName = string.Empty;                var openFileDialog = new OpenFileDialog();                if (openFileDialog.ShowDialog() == DialogResult.OK)                {                    fileName = openFileDialog.FileName;                }                                OleDbConnection conn = new OleDbConnection();                OleDbCommand cmd = new OleDbCommand();                OleDbDataAdapter da = new OleDbDataAdapter();                DataSet ds = new DataSet();                string query = null;                string connString = "";                string strFileName = DateTime.Now.ToString("ddMMyyyy_HHmmss");                string strFileType = System.IO.Path.GetExtension(openFileDialog.FileName).ToString().ToLower();                if (strFileType.Trim() == ".xls")                {                    MessageBox.Show("'xls' is not supported. Please choose the 'xlsx' file extension.");                }                else                {                    if (strFileType.Trim() == ".xls")                    {                        connString = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=" + fileName + ";Extended Properties=\"Excel 8.0;HDR=Yes;IMEX=2\"";                    }                    else if (strFileType.Trim() == ".xlsx")                    {                        connString = "Provider=Microsoft.ACE.OLEDB.12.0;Data Source=" + fileName + ";Extended Properties=\"Excel 12.0;HDR=Yes;IMEX=2\"";                    }                    conn = new OleDbConnection(connString);                    if (conn.State == ConnectionState.Closed) conn.Open();                    string SpreadSheetName = "";                    DataTable ExcelSheets = conn.GetOleDbSchemaTable(System.Data.OleDb.OleDbSchemaGuid.Tables, new object[] { null, null, null, "TABLE" });                    SpreadSheetName = ExcelSheets.Rows[0]["TABLE_NAME"].ToString();                    query = "SELECT * FROM [" + SpreadSheetName + "]";                    cmd = new OleDbCommand(query, conn);                    da = new OleDbDataAdapter(cmd);                    ds = new DataSet();                    da.Fill(ds);                                    }            }            catch (Exception ex)            {                MessageBox.Show("The Import file is failed. \n" + ex.ToString());            }        }