主题：请问这怎么写

Dim Cols1() As String = {"学校名称","年级","班级","学生姓名","身份证件号"}
Dim Cols2() As String = {"单位名称","年级代码","班级","姓名","身份证件号"}
For Each dr1 As DataRow In DataTables("学生信息").DataRows
    Dim dr2 As DataRow = DataTables("成绩").AddNew()
   
    For i As Integer = 0 To Cols1.Length -1
        Select Case i
            Case 0
                dr2(Cols2(i)) = dr1(Cols1(i)).Substring(6,7)
            Case 1
                dr2(Cols2(i)) = dr1(Cols1(i)).Substring(4,2)
               
            Case 2
                                         
        End Select
       
    Next
Next

学生信息表中班级列格式：初中2015级1班，或初中2015级12班，班号有的大于10，成绩表中班级列格式：01或12，请问Case 2怎么写？谢谢

Dim Cols1() As String = {"学校名称","年级","班级","学生姓名","身份证件号"}
Dim Cols2() As String = {"单位名称","年级代码","班级","姓名","身份证件号"}
For Each dr1 As DataRow In DataTables("学生信息").DataRows
    Dim dr2 As DataRow = DataTables("成绩").AddNew()
    For i As Integer = 0 To Cols1.Length -1
        Select Case i
            Case 0
                dr2(Cols2(i)) = dr1(Cols1(i)).Substring(6,7)
            Case 1
                dr2(Cols2(i)) = dr1(Cols1(i)).Substring(4,2)           
            Case 2               
                Dim c() As Char = {"级", "班"}
                Dim str As String = dr1(Cols1(i))
                Dim s1() As String = str.Split(c)
                dr2(Cols2(i)) = format(s1(1),"00")
            Case 3,4
                dr2(Cols2(i)) = dr1(Cols1(i))    
        End Select
       
    Next
Next

请问老师，为什么红色代码填出来班级全为00呢？我是想填为01,02,11,12类似的班号，请指点，谢谢。