请教老师，下面代码，如何在计量列没有数字的时候，维度列也不出现内容，现在的问题是，计量列填入数字后，再删除为空后，维度列依然有内容

datachanged 

Select Case e.DataCol.Name  
    Case "难度赋值_计量"
        Dim dr01 As DataRow = DataTables("难度计量标值").SQLFind("启用 = 1 and 难度因子名称 = \'正常\'")
        Dim dr011 As Double
        dr011 = dr01("难度计量标准值")
        If dr01 IsNot Nothing Then
            If e.DataRow("难度赋值_计量") = dr011  Then
                e.DataRow("难度赋值_维度") = "正常"

         Else

                e.DataRow("难度赋值_维度") = ""
            End If
        End If
End Select

Select Case e.DataCol.Name  
    Case "难度赋值_计量"
        Dim dr1 As DataRow = DataTables("难度计量标值").SQLFind("启用 = 1 and 难度因子名称 = \'稍难1\'")
        Dim dr11 As Double
        dr11 = dr1("难度计量标准值")
        Dim dr2 As DataRow = DataTables("难度计量标值").SQLFind("启用 = 1 and 难度因子名称 = \'稍难2\'")
        Dim dr22 As Double
        dr22 = dr2("难度计量标准值")
        If dr1 IsNot Nothing Then
            If dr2 IsNot Nothing Then
                If e.DataRow("难度赋值_计量") >= dr11  AndAlso e.DataRow("难度赋值_计量") <= dr22  Then
                    e.DataRow("难度赋值_维度") = "稍难"
                End If
            End If
        End If
End Select