private void btnPrint_Click(object sender, EventArgs e){   //打印主从表数据    string file = Application.StartupPath @"\MasterDetail.frx";   rptMasterDetail.Load(file);//加载报表模板文件       DataSet ds = DAL.GetMasterDetailData();//取报表数据       rptMasterDetail.RegisterData(ds.Tables[0], "tb_SO"); //注册数据源,主表    rptMasterDetail.RegisterData(ds.Tables[1], "tb_SOs"); //注册数据源,从表       //    //直接注册DataSet也行，但必须对DataSet.Tables指定表名！    //FastReport是跟据表名取DataTable对象的。    //    //rptMasterDetail.RegisterData(ds);    //       //给DataBand(主表数据)绑定数据源    DataBand masterBand = rptMasterDetail.FindObject("Data1") as DataBand;   masterBand.DataSource = rptMasterDetail.GetDataSource("tb_SO"); //主表       //给DataBand(明细数据)绑定数据源    DataBand detailBand = rptMasterDetail.FindObject("Data2") as DataBand;   detailBand.DataSource = rptMasterDetail.GetDataSource("tb_SOs"); //明细表       //重要！！给明细表设置主外键关系！    detailBand.Relation = new Relation();   detailBand.Relation.ParentColumns = new string[] { "SONO" };   detailBand.Relation.ParentDataSource = rptMasterDetail.GetDataSource("tb_SO"); //主表    detailBand.Relation.ChildColumns = new string[] { "SONO" };   detailBand.Relation.ChildDataSource = rptMasterDetail.GetDataSource("tb_SOs"); //明细表       //准备工作,显示报表预览窗体    rptMasterDetail.Prepare();   rptMasterDetail.ShowPrepared(true, this);   }