Lucky Draw Application

This week our team was tasked to prepare the System to support our annual Dinner. One of the events expected was of course the lucky draw.

First thing, I did was to see how others have done it. An excellent example can be found ind DaniWeb. Which provided me as the basis for the interface to perform the top 5 prizes.

Since the annual dinner will be held off site, we will not have access to the database that contains the employee info. This is resolved by using xml to hold the information and then using DataTable for data manipulation. With this in mind, I created a class to perform the lucky draw using the random number generator as shown below:

' Common Library to be used by the Project
' Date    Feb 29, 2008
' Revised

Imports System.Data.OleDb

Public Class clsDrawLib

Dim _dTab As New DataTable
Dim _dDraw As New DataTable
Dim conn As OleDbConnection
Dim _lastDraw As DataRow

Public Property dataTab()
Get
Return _dTab
End Get
Set(ByVal Value)
_dTab = Value
End Set
End Property

Public Property dataDraw()
Get
Return _dDraw
End Get
Set(ByVal Value)
_dDraw = Value
End Set
End Property

Public ReadOnly Property lastDraw()
Get
Return _lastDraw
End Get
End Property

Public Sub qryData(ByRef lbMsg As ListBox)
conn = New OleDbConnection(System.Configuration.ConfigurationSettings.AppSettings("devdb"))
popListMsg(lbMsg, Now & " - In dbclick")

Try
conn.Open()
popListMsg(lbMsg, Now & " - Connection successful")

Dim dbCmd As OleDbCommand = conn.CreateCommand
Dim sql As String = "select eno, name from empmast where eno like '16%'"
dbCmd.CommandText = sql
Dim dbAdapt As New OleDbDataAdapter
dbAdapt.SelectCommand = dbCmd
dbAdapt.Fill(_dTab)
addRsltCol()

popListMsg(lbMsg, Now & " - Data bound")

Catch ex As Exception
popListMsg(lbMsg, Now & " - Error: " & ex.Message)
Finally
If conn.State = ConnectionState.Open Then
    conn.Close()
End If
End Try

End Sub

Private Sub addRsltCol()
Dim dRow As DataRow = _dTab.NewRow
Dim dCol, dCol2 As DataColumn

_dDraw.Columns.Add("PrizeNum", System.Type.GetType("System.Int32"))

For Each dCol In _dTab.Columns
_dDraw.Columns.Add(dCol.ColumnName, dCol.DataType)
Next

End Sub

Public Sub drawRslt(ByRef lbMsg As ListBox, ByVal pGiftNum As Integer)
Dim colCnt As Integer
Dim giftRow, drawnRow As DataRow
Dim dCol As DataColumn
Dim drawFlg As Boolean

If _dTab.Rows.Count = 0 Then
popListMsg(lbMsg, "Can't proceed - no data available")
Else
'giftNum = CInt(pGiftNum)
'lbmsg.Items.Add("Gift number is " & giftNum)
drawnRow = _dTab.NewRow

drawFlg = clsDraw.clsDraw.drawRec(_dTab, drawnRow)
giftRow = _dDraw.NewRow
giftRow.Item(0) = pGiftNum
colCnt = 0

Do While colCnt < _dTab.Columns.Count
        giftRow.Item(colCnt + 1) = drawnRow.Item(colCnt)
        colCnt += 1
    Loop

    _lastDraw = giftRow

    _dDraw.Rows.Add(giftRow)
    'dgRslt.DataSource = dDraw

End If

End Sub


Sub popListMsg(ByRef lbMsg As ListBox, ByVal msg As String)
If (lbMsg Is Nothing) = False Then
    lbMsg.Items.Add(msg)
End If
End Sub

End Class

The above class can then be used to select the lucky record and can be used either for the table draw or the individual employee draw.

Additional things added for the interface of the lottery is as follows

The following sample queries from a database but in the actual windows application, it will obtain the data from an XML file.

I then obtain the DataRow of the lucky number from the clsDraw class shown above and then use multiple threads to simulate the drawing and then start populating the number one at a time until all the numbers of the employee number is displayed.

There is one thread which will in turn generate six threads (one for each number assuming the employee number is six digit. I keep track of the threads in an Arraylist and join to the thread so that it won't continue until the thread is complete.

The main thread will be in charge of going through each of the numbers and ensuring that the remaining digits continue to spin until all the numbers are displayed. The other threads are the ones that actually perform the number movement.

    Private Sub btnDraw_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnDraw.Click
    Dim empName As String

    If Microsoft.VisualBasic.IsNumeric(tbNum.Text) = True Then
        lblName.Text = "drawn"
        If CType(_drawObj.dataTab, DataTable).Rows.Count <= 0 Then
            _drawObj.qryData(Nothing)
        End If
        _drawObj.drawRslt(Nothing, tbNum.Text)
        'displayRnd()
        drawnRow = _drawObj.lastDraw
        eno = drawnRow.Item(1)
        empName = drawnRow.Item(2)
        lblName.Text += vbNewLine & eno
        displayENO2(eno)
        lblName.Text = empName

    Else
        lblName.Text = "No draw"
    End If
End Sub

==================
Private Sub displayENO2(ByVal eno As String)
   Dim tmpStr, tmpStr2, ctrlName As String
   Dim i, loc, loc2 As Integer
   Dim thrd As System.Threading.Thread

   aList.Clear()


   For i = 1 To 6
       tmpStr = "txtN" & i
       aList.Add(tmpStr)
   Next

   loc = 6 - eno.Length
   tmpStr = eno

   For i = 0 To eno.Length - 1
       'rndDispList(aList)
       thrd = New System.Threading.Thread(AddressOf rndDispList)
       thrd.Start()
       loc2 = loc - 1
       tmpStr2 = Microsoft.VisualBasic.Right(tmpStr, 1)
       tmpStr = Microsoft.VisualBasic.Left(tmpStr, tmpStr.Length - 1)
       ctrlName = "txtN" & (6 - i)
       thrd.Join()
       setTxtBoxVal(ctrlName, tmpStr2)
       aList.Remove(ctrlName)
   Next

End Sub

Sub rndDispN1()
   rndDisp("txtN1")
End Sub
Sub rndDispN2()
   rndDisp("txtN2")
End Sub
Sub rndDispN3()
   rndDisp("txtN3")
End Sub
Sub rndDispN4()
   rndDisp("txtN4")
End Sub
Sub rndDispN5()
   rndDisp("txtN5")
End Sub
Sub rndDispN6()
   rndDisp("txtN6")
End Sub

Private Sub rndDispList()
   Dim ctrlName As String
   Dim thrd As System.Threading.Thread
   Dim tList As New ArrayList

   For Each ctrlName In aList
       Select Case ctrlName
           Case "txtN1"
               thrd = New System.Threading.Thread(AddressOf rndDispN1)
               thrd.Start()
               tList.Add(thrd)
           Case "txtN2"
               thrd = New System.Threading.Thread(AddressOf rndDispN2)
               thrd.Start()
               tList.Add(thrd)
           Case "txtN3"
               thrd = New System.Threading.Thread(AddressOf rndDispN3)
               thrd.Start()
               tList.Add(thrd)
           Case "txtN4"
               thrd = New System.Threading.Thread(AddressOf rndDispN4)
               thrd.Start()
               tList.Add(thrd)
           Case "txtN5"
               thrd = New System.Threading.Thread(AddressOf rndDispN5)
               thrd.Start()
               tList.Add(thrd)
           Case "txtN6"
               thrd = New System.Threading.Thread(AddressOf rndDispN6)
               thrd.Start()
               tList.Add(thrd)
           Case Else
       End Select
   Next

   For Each thrd In tList
       thrd.Join()
   Next

End Sub