AUTO INCREMENT CODE IN VB.NET

    Sub ldfrm()
        Dim connetionString As String = Nothing
        Dim connection As SqlConnection
        Dim command As SqlCommand
        Dim adapter As New SqlDataAdapter()
        Dim ds As New DataSet()

        Dim sql As String = Nothing
        connetionString = "Data Source=KEERTIG-PC\SQLEXPRESS;Initial Catalog=GAURAV1;Integrated Security=True"

        sql = "Select  * from ROOM_BOOKING"

        connection = New SqlConnection(connetionString)

        Try
            connection.Open()
            command = New SqlCommand(sql, connection)
            adapter.SelectCommand = command
            adapter.Fill(ds, "ROOM_BOOKING")
            adapter.Dispose()
            command.Dispose()
            connection.Close()

        Catch ex As Exception
            MessageBox.Show("Can not open connection ! ")
        End Try

        Dim dt As DataTable
        Dim dr As DataRow

        dt = ds.Tables("ROOM_BOOKING")
        Dim ctr, len As Integer
        Dim stdid, stdidval As String

        len = dt.Rows.Count - 1
        If len = -1 Then
            TXTBSBID.Text = "B001"
        Else
            dr = dt.Rows(len)
            stdid = dr("ROOMBK_ID")
            stdidval = Mid(stdid, 2, 4)
            ctr = CInt(stdidval)
            If ctr >= 1 And ctr < 9 Then
                ctr = ctr + 1
                TXTBSBID.Text = "B00" & ctr
            ElseIf ctr >= 9 And ctr < 99 Then
                ctr = ctr + 1
                TXTBSBID.Text = "B0" & ctr
            ElseIf ctr >= 99 And ctr < 999 Then
                ctr = ctr + 1
                TXTBSBID.Text = "B" & ctr

            End If
        End If

    End Sub

    Private Sub BTNADDID_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles BTNADDID.Click
        ldfrm()

    End Sub