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Transaction processing program with random access files

Transaction processing program with random access files

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Transaction processing program with random access files

Option Explicit

Private Type ClientRecord
   accountNumber As Integer
   lastName As String * 15
   firstName As String * 15
   balance As Currency
End Type

Dim mUdtClient As ClientRecord   user defined type

Private Sub Form_Load()
   tabOperations.Enabled = False
End Sub

Sub cmdOpenFile_Click()
   Dim recordLength As Long
   Dim filename As String
   
   Determine number of bytes in a ClientRecord object
   recordLength = LenB(mUdtClient)
   
   dlgOpen.ShowOpen
   filename = dlgOpen.filename

   If dlgOpen.FileTitle <> "" Then
      Open file for writing
      Open filename For Random Access Read Write As #1 _
         Len = recordLength
      cmdOpenFile.Enabled = False  Disable button
      cmdCloseFile.Enabled = True
      tabOperations.Enabled = True
   Else
      MsgBox ("You must specify a file name")
   End If
End Sub

Create a text file representation of the random-access file
Private Sub cmdTextFile_Click()
   Dim filename As String, balanceString As String
   
   On Error Resume Next
   dlgTextFile.ShowOpen
   filename = dlgTextFile.filename
   
   If dlgTextFile.FileTitle <> "" Then
      Open file for writing
      Open filename For Output Access Write As #2
      Print #2, "Account";
      Print #2, Tab(10); "First Name";
      Print #2, Tab(28); "Last Name";
      Print #2, Tab(46); Format("Balance", "@@@@@@@@@@")
      
      Seek #1, 1            reposition to start of file
      Get #1, , mUdtClient  read first record
      
      While Not EOF(1)
         If mUdtClient.accountNumber <> 0 Then
            Print #2, mUdtClient.accountNumber;
            Print #2, Tab(10); mUdtClient.firstName;
            Print #2, Tab(28); mUdtClient.lastName;
            balanceString = _
               Format(mUdtClient.balance, "0.00")
            Print #2, Tab(46);
            Print #2, Format(balanceString, "@@@@@@@@@@")
            
         End If
         
         Get #1, , mUdtClient  'read next record
      Wend
      
      Close #2
   Else
      MsgBox ("You must specify a file name")
   End If
End Sub

Add a new record to the file
Private Sub cmdAddNew_Click()
   If txtNewAccount.Text <> "" Then
      Get #1, Val(txtNewAccount), mUdtClient  'read record
      
      If mUdtClient.accountNumber = 0 Then
         mUdtClient.accountNumber = Val(txtNewAccount)
         mUdtClient.firstName = txtNewFirstName.Text
         mUdtClient.lastName = txtNewLastName.Text
         mUdtClient.balance = txtNewBalance.Text
         Put #1, mUdtClient.accountNumber, mUdtClient
         MsgBox ("Account " & mUdtClient.accountNumber & _
                 " has been added to the file")
      Else
         MsgBox ("Account already exists")
      End If
   Else
      MsgBox ("You must enter an account number")
   End If
End Sub

Update an existing record
Private Sub cmdUpdate_Click()
   Dim account As Integer, transactionAmount As Double
   On Error Resume Next
   
   account = Val(InputBox("Enter account number"))
   Get #1, account, mUdtClient  'read record
   
   If mUdtClient.accountNumber <> 0 Then
      txtUpdateAccount.Text = Str$(mUdtClient.accountNumber)
      txtUpdateFirstName.Text = mUdtClient.firstName
      txtUpdateLastName.Text = mUdtClient.lastName
      txtUpdateBalance.Text = Str$(mUdtClient.balance)
      transactionAmount = Val(InputBox( _
         "Enter transaction amount. Positive for charge. " & _
         "Negative for payment."))
      mUdtClient.balance = _
         mUdtClient.balance + transactionAmount
      txtUpdateBalance.Text = Str$(mUdtClient.balance)
      Put #1, mUdtClient.accountNumber, mUdtClient
   Else
      MsgBox ("Record " & account & " does not exist")
   End If

End Sub

Delete the specified record
Private Sub cmdDelete_Click()
   Dim blankClient As ClientRecord
   On Error Resume Next
   
   Get #1, Val(txtDelete.Text), mUdtClient  'read record
   
   If mUdtClient.accountNumber <> 0 Then
      Put #1, mUdtClient.accountNumber, blankClient
      MsgBox ("Account # " & mUdtClient.accountNumber & _
         " has been deleted")
   Else
      MsgBox ("Record does not exist")
   End If
End Sub

Sub cmdCloseFile_Click()
   Close #1
   cmdOpenFile.Enabled = True
   cmdCloseFile.Enabled = False
End Sub

Private Sub Form_Terminate()
   Close
End Sub

Private Sub cmdExit_Click()
   Close
   End
End Sub