private void btnCSV_Click(object sender, EventArgs e)
{
string access = @"DB\WinFramework.mdb";
OleDbHelper helper = new OleDbHelper(access);
string sql = string.Format("Select * from mps_MailDetail ");
DataTable dt = helper.ExecuteDataSet(sql).Tables[0];
//导出到CSV文件
string fileName = Path.Combine(Application.StartupPath, "mps_MailDetail.csv");
CSVHelper.DataTableToCSV(dt, fileName);
//从CSV文件导入到DataTable
DataTable dtNew = CSVHelper.CSVToDataTableByOledb(fileName);
this.dataGridView1.DataSource = dtNew.DefaultView;
}