How do you write code for a flat file database??

[Shane Ottens]

I am just learning VB6 and have an exercise that I need to complete using a flat file database (I assume random access). I just don't know exactly where to start? Can any one give me some direction?

[Serge]

Flat file is not a database. Well, you can kind of call it as a table.

Here is an exaple of using Random Access file.
Let's say you have an information of a Customer. Here are the fields that we're going to have:

• CustomerID
• LasName
• FirstName
• Address
• City
• State
• Zip

First, we would create a User Defined Data Type to hold that customer information, then use that UDT to save the Customer record. For this purpose we would create 7 TextBoxes (txtCustomerID, txtLastName, txtFirstName, txtAddress, txtCity, txtState and txtZip). Also, let's add 2 buttons to your form (cmdSave and cmdNew):

Private Type udtCustomer
    lngCustomerID As Long
    strLasName As String * 15
    strFirstName As String * 15
    strAddress As String * 25
    strCity As String * 15
    strState As String * 2
    strZip As String * 5
End Type

Private Sub cmdNew_Click()
    Dim txt As Control
    
    For Each txt In Me.Controls
        If TypeOf txt Is TextBox Then
            txt.Text = ""
        End If
    Next
End Sub


Private Sub cmdSave_Click()
    Dim intFFN As Integer ' to hold next free file number
    Dim strPath As String 'Path to the file
    Dim tCustomer As udtCustomer 'variable to hold Customer info
    
    
    strPath = "D:\Customer.txt"
    intFFN = FreeFile
    
    'First get the last CustomerID
    'so we can generate next one
    Open strPath For Random As intFFN Len = Len(tCustomer)
    Get #intFFN, , tCustomer
    
    
    'Get Customer Information
    With tCustomer
        'Increment ID
        .lngCustomerID = tCustomer.lngCustomerID + 1
        .strLasName = txtLastName
        .strFirstName = txtFirstName
        .strAddress = txtAddress
        .strCity = txtCity
        .strState = txtSate
        .strZip = txtZip
    End With
    
    'Save the record
    Put #intFFN, , tCustomer
    'Show the new generated ID in the TextBox
    txtCustomerID = tCustomer.lngCustomerID
    'Close the file
    Close #intFFN
End Sub


Private Sub Form_Load()
    Dim strPath As String
    Dim intFFN As Integer
    
    intFFN = FreeFile
    strPath = "D:\Customer.txt"
    'If Customer.txt doesn't exit then create it.
    If Dir(strPath) = "" Then
        Open strPath For Output As intFFN
        Close #intFFN
    End If
End Sub

This is a small exaple of how to save the Customer info to the Random file. Check out MSDN as it has many examples of how to work with flat files.