// private clsMysqlConexion objmysql;
private void btBuscar_Click(object sender, EventArgs e)
{
clsMysqlConexion objmysql = new clsMysqlConexion();
String atributos = "fechayhora,id_linea,id_tarjeta,credito";
String cdgo_t = (CBOX1.Checked) ? tbcdgo.Text : "";
DataTable dt = objmysql.BuscarActividadTbl(atributos, dtinicio, dtfinal, cdgo_t, rbt1.Checked, rbt2.Checked);
DataRow[] dr = dt.Select();
decimal fltTotal = 0;
for (int i = 0; i < dr.Length; i++)
{
fltTotal += Convert.ToDecimal(dr[i]["credito"]);
}
TBOX1.Text = fltTotal.ToString();
dtgv.DataSource = dt;
}