用DataView求聚合函数,该如何处理

用DataView求聚合函数
想通过用DataView求聚合函数，下面的代码出错，不知道如何修改，请教大家！谢谢！

C# code

            DataSet ds = new DataSet();            DataTable Course = new DataTable("Course");            Course.Columns.Add("Id", typeof(System.Int32));            Course.Columns.Add("Name", typeof(System.String));            Course.Rows.Add(1, "ASP.NET");            ds.Tables.Add(Course);            DataTable Student = new DataTable("Student");            Student.Columns.Add("Id", typeof(System.Int32));            Student.Columns.Add("Name", typeof(System.String));            Student.Columns.Add("Age", typeof(System.Int32));            Student.Columns.Add("courseId", typeof(System.Int32));            Student.PrimaryKey = new DataColumn[] { Student.Columns["Id"] };            ds.Tables.Add(Student);            Student.Rows.Add(1, "王伟", 20, 1);            Student.Rows.Add(2, "李伟", 18, 1);            Student.Rows.Add(3, "刑天", 18, 1);            DataRelation rel = new DataRelation("relTable",                new DataColumn[] { Course.Columns["Id"] },                new DataColumn[] { Student.Columns["courseId"] });            ds.Relations.Add(rel);            DataView dv = new DataView();            dv.Table = ds.Tables["Student"];            dv.RowFilter = "max(Child(relTable).Age) > 0";            GridView1.DataSource = dv;            GridView1.DataBind();

C# code

dv.Table = ds.Tables["Student"];dv.RowFilter = "max(Child(relTable).Age) > 0";=>dv.Table = ds.Tables["Course"];dv.RowFilter = "max(Child(relTable).Age) > 0";