Сохранить данные из ListView в базу SQL без дубликатов

Dim iCount As Integer
        Dim iLoop As Integer
        Dim query3 As New SqlCommand
        Dim lvitem
        query3.Connection = New SqlConnection("Server= '" & TextBox1.Text & "' ; Database = DBName; Integrated Security = true")
        query3.Connection.Open()
 
        iCount = lvLogs.Items.Count
        ' For iLoop = 0 To lvLogs.Items.Count - 1
        If Not lvLogs.Items.Count = 0 Then
            Do Until iLoop = lvLogs.Items.Count
 
                lvitem = lvLogs.Items.Item(iLoop)
 
                With lvitem
 
                    query3.CommandText = "insert into DataLog values ('" & lvitem.subitems(0).text & "','" & lvitem.subitems(1).text & "','" & lvitem.subitems(2).Text & "','" & lvitem.subitems(3).Text & "','" & lvitem.subitems(4).Text & "','" & lvitem.subitems(5).Text & "') "
 
                    query3.ExecuteNonQuery()
                End With
 
                iLoop = iLoop + 1
                lvitem = Nothing
            Loop
            MsgBox("done")
        End If

#Region "AttLogs"
    Private Sub btnGetGeneralLogData_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnGetGeneralLogData.Click
If bIsConnected = False Then
            MsgBox("Please connect the device first", MsgBoxStyle.Exclamation, "Error")
            Return
        End If
        If axCZKEM1.GetDeviceStatus(iMachineNumber, 6, iValue) = True Then 'Here we use the function "GetDeviceStatus" to get the record's count.The parameter "Status" is 6.
            ToolStripLabel1.Text = "The count in the device is :   " + iValue.ToString()
 
 
            ' "The count of the AttLogs in the device is " & "+ iValue.ToString()"
        End If
 
        Dim sdwEnrollNumber As String = ""
        Dim idwVerifyMode As Integer
        Dim idwInOutMode As Integer
        Dim idwYear As Integer
        Dim idwMonth As Integer
        Dim idwDay As Integer
        Dim idwHour As Integer
        Dim idwMinute As Integer
        Dim idwSecond As Integer
        Dim idwWorkcode As Integer
 
        Dim idwErrorCode As Integer
        Dim iGLCount = 0
 Cursor = Cursors.WaitCursor
  axCZKEM1.EnableDevice(iMachineNumber, False) 'disable the device
        If axCZKEM1.ReadGeneralLogData(iMachineNumber) Then 'read all the attendance records to the memory
            'get records from the memory
            While axCZKEM1.SSR_GetGeneralLogData(iMachineNumber, sdwEnrollNumber, idwVerifyMode, idwInOutMode, idwYear, idwMonth, idwDay, idwHour, idwMinute, idwSecond, idwWorkcode)
                iGLCount += 1
  If DataGridView1.DataSource Is Nothing Then
                    With DataGridView1
                        .Rows.Add(iGLCount.ToString, sdwEnrollNumber, idwVerifyMode.ToString, idwInOutMode.ToString, idwYear.ToString() & "-" + idwMonth.ToString() & "-" & idwDay.ToString() & " " & idwHour.ToString() & ":" & idwMinute.ToString() & ":" & idwSecond.ToString(), idwWorkcode.ToString)
                    End With
 
 
                End If
 
 
            End While
        Else
            Cursor = Cursors.Default
            axCZKEM1.GetLastError(idwErrorCode)
            If idwErrorCode <> 0 Then
                MsgBox("Reading data from terminal failed,ErrorCode: " & idwErrorCode, MsgBoxStyle.Exclamation, "Error")
            Else
                MsgBox("No data from terminal returns!", MsgBoxStyle.Exclamation, "Error")
            End If
        End If
 
        axCZKEM1.EnableDevice(iMachineNumber, True) 'enable the device
        Cursor = Cursors.Default
    End Sub

                    
query3.CommandText = "WHERE NOT EXISTS INSERT INTO DataLog VALUES('" & lvitem.subitems(0).text & "','" & lvitem.subitems(1).text & "','" & lvitem.subitems(2).Text & "','" & lvitem.subitems(3).Text & "','" & lvitem.subitems(4).Text & "','" & lvitem.subitems(5).Text & "') "

query3.CommandText = "INSERT INTO DataLog VALUES('" & lvitem.subitems(0).text & "','" & lvitem.subitems(1).text & "','" & lvitem.subitems(2).Text & "','" & lvitem.subitems(3).Text & "','" & lvitem.subitems(4).Text & "','" & lvitem.subitems(5).Text & "') "
 
Select 'Date' Where not exists(select * from DataLog where Date='lvitem.subitems(2).text')

 Private Sub btnSavetoDB_Click(sender As System.Object, e As System.EventArgs) Handles btnSavetoDB.Click
        Dim cmdsql As SqlCommand
        For row As Integer = 0 To DataGridView1.RowCount - 6
            Call connectsql()
            Dim simpan As String = "INSERT INTO DataLog VALUES ('" & DataGridView1.Rows(row).Cells(0).Value & "', '" & DataGridView1.Rows(row).Cells(1).Value & "', '" & DataGridView1.Rows(row).Cells(2).Value & "', '" & DataGridView1.Rows(row).Cells(3).Value & "', '" & DataGridView1.Rows(row).Cells(4).Value & "', '" & DataGridView1.Rows(row).Cells(5).Value & "') " & "Select 'Date' Where Not exists(select * from DataLog where Date='lvitem.subitems(2).text')"
 
            cmdsql = New SqlCommand(simpan, connsql)
            cmdsql.ExecuteNonQuery()
        Next
        MsgBox("Data Saved!")