Dim b As New SQLGroupTableBuilder("统计表2","视力健康")
b.C
b.Groups.AddDef("班级")
b.Totals.AddExp("班级人数","学生姓名","",AggregateEnum.Count) '统计人数
Dim nms() As String = {"近视人数"}
For Each nm As String In nms '利用表达式统计及格人数和优秀人数
b.Totals.Addexp(nm & "近视人数", "case when (裸眼视力左眼 < 4.8 And 裸眼视力右眼 < 4.8 , 1, 0)")
Next
b.VerticalTotal = True
b.Build()
For Each nm As String In nms '对生成的统计表增加表达式列,计算及格率和优秀率
DataTables("统计表2").DataCols.Add(nm & "近视率",Gettype(Double), nm & "近视人数/班级人数" )
Tables("统计表2").Cols(nm & "近视率").Move(Tables("统计表2").Cols(nm & "近视人数").Index + 1)
'Next
MainTable = Tables("统计表2")
想要按班级统计学生人数和近视人数,并计算出近视率,一直不能成功,应该怎么修改呢?