class=" + comboClass.SelectedValue.ToString() + " order by class,srid" 少了单引号
改成
class='" + comboClass.SelectedValue.ToString() + "' order by class,srid"
dt = sql.SelectSql("select * from einfo where SchID ='" + dt.Rows[0]["SchID"].ToString() + "' and class=" + comboClass.SelectedValue.ToString() + " order by class,srid");
是这句,不好意思.
dt = sql.SelectSql("select * from einfo where SchID ='" + dt.Rows[0]["SchID"].ToString() + "' and class=" + comboClass.SelectedValue.ToString() + " order by class,srid");