主题：重复数据的排除？

Dim dlg As New OpenFileDialog '定义一个新的OpenFileDialog
dlg.Filter= "Excel文件|*.xls|Word文件|*.doc|Access文件|*.mdb" '设置筛选器
If dlg.ShowDialog = DialogResult.Ok Then '如果用户单击了确定按钮
    Dim Book As New XLS.Book(dlg.FileName)
    Dim Sheet As XLS.Sheet = Book.Sheets(0)
    Dim kqsj As Date = Functions.Execute("自定义时间",8,30,0)  '定义正常上班时间8:30
    Dim kqsj2 As Date = Functions.Execute("自定义时间",10,30,0)   '定义上午考勤最后有效时间10:30
    Dim kqsj3 As Date = Functions.Execute("自定义时间",11,0,0)    '定义上午缺席时间11:00
    Dim kqsj4 As Date = Functions.Execute("自定义时间",14,30,0)    '定义下午上班时间14:30
    Dim kqsj5 As Date = Functions.Execute("自定义时间",15,30,0)    '定义下午考勤最后有效时间8:30
    Dim kqsj12 As Date = Functions.Execute("自定义时间",12,00,0)    ''定义考勤时间12:00
   
    '注意下面的循环变量从1开始,而不是从0开始,因为Excel表的第一行是标题
    For n As Integer = 4 To 10 Step 2
        Output.Show(Sheet(n,2).Value)
        Output.Show(Sheet(n,10).Value)
        Dim p As String = Sheet(n+1,1).Value
        Dim r As Row = Tables("表A").addnew
        r("工号")=Sheet(n,2).Value
        r("姓名") =Sheet(n,10).Value
        Dim zd As New Dictionary(Of Integer,String)
        For Each s As String In p.Replace(vbcr,"").Split(vblf)
           
           
            Dim s1 As Date
            If Date.TryParse(s, s1) Then
                messagebox.Show(s1)
                r("考勤时间") = r("考勤时间") & s1
                '----判断是否按时上班(8:30以前)------
                If s1 < kqsj   Then
                    If zd.ContainsValue("上午正常") = False  Then
                        zd.Add(1,"上午正常")
                        r("sw")=zd(1)
                    End If
                End If
                '-----'----判断是否迟到(8:30至10:30)------
                If s1 > kqsj And s1 < kqsj2   Then
                    If zd.ContainsValue("上午正常") = False  Then
                        If zd.ContainsValue("上午迟到") = False Then
                            zd.Add(2,"上午迟到")
                        End If
                        r("sw")=zd(2)
                    End If
                End If
                '------------判断是否缺席(晚于11:00或缺席)------
                If s1 > kqsj3  Then
                    If zd.ContainsValue("上午正常") = False AndAlso zd.ContainsValue("上午迟到") = False Then
                        If zd.ContainsValue("上午缺席") = False Then
                            zd.Add(3,"上午缺席")
                        End If
                        r("sw")=zd(3)
                    End If
                End If
                '------------判断下午是否正常上班(早于14:30或缺席)------
               
                If s1 > kqsj12  And s1< kqsj4 Then
                    If zd.ContainsValue("下午正常") = False
                        zd.Add(4,"下午正常")
                        r("xw")=zd(4)
                    End If
                End If
                '------------判断下午是否迟到(14:30-15:30)------
                If s1 > kqsj4  And s1< kqsj5 Then
                    If zd.ContainsValue("下午正常") = False
                        If zd.ContainsValue("下午迟到") = False Then
                            zd.Add(5,"下午迟到")
                        End If
                        r("xw")=zd(5)
                    End If
                End If
                '------------判断下午是否缺席 (晚于15:30)------
                If s1 >= kqsj5    Then
                    If zd.ContainsValue("下午正常") = False  AndAlso zd.ContainsValue("下午迟到") = False Then
                        If zd.ContainsValue("下午缺席") = False Then
                            zd.Add(6,"下午缺席")
                        End If
                        r("xw")=zd(6)
                    End If
                End If
               
            End If
           
        Next
       
        zd.Clear
    Next
End If

If Date.TryParse(s, s1) Then

    '本来代码

Else

    '新的逻辑代码

End If

 

如果要判断是不是空，这样写

 

Dim s1 As Date = Nothing
Date.TryParse(s, s1)

If s1 = Nothing Then

 

End If