id generator code problem

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VB

SQL-Server

hw u doing coders .. am facing problem with my code of id number generator
i am building database project and i want to make the id generates it self automaticaly i did it but not how i want it to work ...i want it to Start from 001 and increases every time +1 like this 002,003 untill it reach 100 and so on
how it works now is like this starts from 1 and then 2,3,4,5,6......here is the code.
thank you.

Sub GenerateSerialNo()
        Dim odr As SqlDataReader
        Dim sql As String
        sql = "select max(bookid)as SNo from tbremovedbooks"
        Try
            conn.Open()
            'Application.DoEvents()
            cmd = New SqlCommand(sql, conn)
            odr = cmd.ExecuteReader
            If odr.Read() Then
                iNumOfRecords = DS.Tables("tbremovedbooks").Rows.Count + 1
                'Displaying 1 if there is no data in the table
                If iNumOfRecords = 1 Then
                    txtbookid.Text = "1"
                Else
                    'Ordering the data Serial if more than one record is in the table
                    txtbookid.Text = odr("SNo") + 1
                End If
            End If
            odr.Close()
            cmd.Connection.Close()
            conn.Close()
        Catch ex As Exception
            MsgBox(ex.Message)
        End Try
    End Sub