Function Parameter ByVal and ByRef Usage

Introduction.

Before taking up the above subject, let us look at some fundamentals of the variables for the benefit of novices.

When we define a variable in VBA or in any other programming language, the computer reserves some memory location and allocates some memory cells (the number of cells allocated depends on the declared variable type, like Integer, Double, String, etc.) to store values passed to it. 

In layman's analogy, we can imagine a variable as a box with the name 'Apple' or whatever name we give to the box and uses that name to pick the value stored in it.  Assume that you have put 5 in the Apple box.  We can give these apples to someone in two ways.

1. Make copies of the apples (the number) from the box ourselves and put them into another box and pass it.  The target box's name will be different.  The recipient of the new box can work with his copy of the apples, like adding more apples in his box or removing some of them, etc.  There will not be any change in the first box's contents. 
2. We can tell the other person (or Function), which area of the room (location) you have kept the original box of apples, get the box contents from there, and work with it.  In this room (or within the function body) there may be other boxes (Variables) with different names and contents.

Making Copies of Original Values.

In the first method explained above, unlike the physical box, you can make copies of the original value and store them in different Variables.  The original value will not change in the first Variable.  The Function that gets the new Variable with the copy has no access to the first Variable.  He can do whatever he wants to do with the copy he has.

In the second case you can tell the location of the Apple_Box1 to the other Function so that it can go there and find its contents and do whatever the Function wants to do with them (add, subtract, multiply, etc., or use it as part of other calculations) or whatever operations you would like to do with them. 

To prove the first point above, let us take a closer look at the next two example functions Test_1A() (the calling function) and Test_1B() (the called function with the copy of the value).

Method-1 Examples:

Public Function Test_1A()

'Define two variables(boxes)to hold values of
'Long Integer type
Dim Apple_Box1 As Long, ApplesReceived As Long

'Put an initial value of 10

'into the variable

Apple_Box1 = 10

'sending a copy of Apple_Box1 Value to Apple_Box2

'Whatever value changes happened in Apple_Box2 in Test_1B()
'Received back into the third box:ApplesReceived

ApplesReceived = Test_1B(Apple_Box1)

'call funcction Test_1B() with the value
'Display the result in MsgBox.
MsgBox "Apple_Box1: " & Apple_Box1 & vbLf & "Apple_Box2 contents: " & ApplesReceived

End Function

In the above program, we are defining two Variables Apple_Box1 and ApplesReceived both to store Long Integer type values. Here, we are not going to bother about what is Long Integer or Short Integer and the range of values that we can store in them, etc.

Next line Apple_Box1 = 10, the value 10 is stored in Apple_Box1. 

The next three lines are remarks explaining what we are doing in the next line. 

We are calling Test_1B() Function and passing the value of Apple_Box1 to the function to do something with the value received in a Variable (ByVal Apple_Box2).  The ByVal before Apple_Box2 given in Test_1B() function states that take a copy of the value from Apple_Box1.  The ‘As Long’ appearing after the closing parenthesis indicates that the second function does some calculations with the received value and returns the result to the first function.  The new value received is stored in ApplesReceived Variable. 

Next line MsgBox() function displays the Apple_Box1 contents and the result value (after modification done to the original copy of the value) received from Test_1B() function.

The Test_1B Function.

Public Function Test_1B(ByVal Apple_Box2 As Long) As Long

'Take Note of the Key-Word 'ByVal' (says take a Copy of the Passed Value)
'Return the value back into the first function Test_1A
'After adding 15 to the original value of 10
'copied into Apple_Box2

Test_1B = Apple_Box2 + 15

End Function

There is only one executable statement in the above function.  Immediately after the function definition, four lines of remarks indicate what happens in the function.

We will take a closer look at the next line of the statement. This statement has two parts – the first part appears left of the = sign and the second part is on the right side of the equal sign. 

In this expression, the left side of the equal sign will be a Variable or a Function name.  By now you will be asking yourself why a function name is there. That will be explained in a moment.

The computer always evaluates the expression given on the right side of the equal sign first and arrives at a single value and moves that result in the Variable given on the left side of the equal sign.  Any existing value in the variable will be lost. You can write that expression in two lines to arrive at the same result as below:

Apple_Box2 = Apple_Box2 + 15

Test_1B = Apple_Box2

In the first expression, you can see that we have used the Apple_Box2 variable on the left side and right side of the = sign. As I said earlier the expression on the right side of the equal sign is evaluated first. So it takes the existing value of 10 from Apple_Box2 for calculations and Adds 15, arriving at the single result value of 25, and moves that value into Variable Apple_Box2, replacing the earlier value of 10.

If the Function name (the function name given in the first line of Code) appears on the left side of the equal sign, then the meaning of the statement is that the final result of the expression must be returned to the Calling Function.  Here, the Function Name acts as a Variable with the Data Type (As Long) specified immediately after the closing brackets on the first line.

This function name appears on the calling statement in the calling function to the right side of the = sign and a Variable Name on the left side of the = sign that saves the received result value (ApplesReceived = Test_1B(Apple_Box1).

Method-2 Examples:

In this method, we have defined only one variable Apple_Box1 as a Long Integer Type.  In the next line, the Variable is loaded with an initial value of 10.  The next two lines are remarks explaining what is happening in the next line that calls the second function Test_1D().

Compare this statement with the statement that calls Test_1B.  Unlike the statement that calls Test_1B() the Function Name Test_1D and the function parameter, Variable Apple_Box1 only appear here.  The opening and closing brackets are omitted from the function name. The parameter variable is the second item.  Test_1D() function is not returning any value back into the calling function Test_1C.  Therefore, we don't need to write this line of code in the form of an expression as we did in Test_1A Function.  But, you cannot write the statement as:

Test_1D(Apple_Box1).,

Once we use the parenthesis (normally used with the function name) around the parameter variable, then VBA assumes that some value is returned from the called function and you are forced to write it like we did it in Function Test_1A:

x = Test_1D(Apple_Box1) 'Expression
'OR use Call statement 
Call Test_1D(Apple_Box1)

There will not be any value in the variable x because no value is returned from the called function.

If you feel comfortable with this method, then you may do so. You will be defining one more variable for this purpose and your program takes up more memory.

The usage of the Call statement requires the parenthesis around the parameter variable. If no parameters to pass to the called function even then you should use the opening and closing parenthesis at the end of Function Name like Call Test_1D().

When control returns from Test_1D() the next line displays the changed value in Apple_Box1 Variable.

Public Function Test_1C()
Dim Apple_Box1 As Long

'put 10 into Variable
Apple_Box1 = 10

'here Test_1D function takes the
'location address of Apple_Box1

Test_1D Apple_Box1 'compare this statement with Test_1A function

MsgBox "Apple_Box1: " & Apple_Box1 & vbLf & "Apple_Box2 contents: " & ApplesReceived

End Function

Test_1D() function takes the location address of the parameter variable passed to it. It works directly with the value stored in the variable Apple_Box1's own location.

Public Function Test_1D(ByRef Apple_Box2 As Long)

Apple_Box2 = Apple_Box2 + 15

End Function

 Test_1D() takes the location address (this is the memory location, number of the variable) of variable Apple_Box1 into variable Apple_Box2, defined in the parameter area of Test_1D() function.

Now, look at the expression:

Apple_Box2 = Apple_Box2 + 15

Apple_Box2 contains the location address, not the contents of the Apple_Box1 variable. But, no need to make any change in the expression to do any kind of calculations.  The computer uses the location address to pick the value from there and use the value in calculations.

Even though we have used ByRef to the Parameter Variable, to accept the location address of the variable passed to it (always a number irrespective of different variable types), the rest of the parameter definition is like any other variable with variable Type (as Long) specification.  Compare Test_1D() function definition with the Test_1B().  Test_1D doesn't have the As Long at the end of the line because it is not returning any value from the function but it changes the original value at its location directly. 

You may omit the usage ByRef from the Function declaration. By default, VBA assumes that the Function Parameter declaration is ByRef (By Reference) if you have not explicitly defined the parameter as ByVal like:

Public Function Test_1D(Apple_Box2 As Long)

Each Variable Type, like Byte, Integer, Long (integer), Double, String, etc., gets allocated with enough memory cells, besides its own address, to hold their maximum range of values. This is different between Programming Languages: VBA, C, C++, C#, etc.

In Conclusion.

We don't have to bother about going too deep into all those things, but it does no harm to have a basic understanding of them.

If you get in touch with the C language and its variants, like the examples given above, you need to deal with these things, sooner or later.

Our discussion here was on a single variable and its value. How we can work with an Array of Variables and Values. We will explore its methods in the coming weeks.

• Useful Report Functions
• Join Split Array Functions
• Join Split Array Functions-2
• Macros and Temporary Variables
• Sub-query in Query Column Expressions

Read More

DIRectory and File Copy Utility

Introduction.

Last week we saw how to use Dir () DOS Command, its ability to read files from the Disk one by one and display it in the Debug Window.

In continuation of that, we will create a VBA Utility using DIR Command with a very useful VBA Statement FileCopy (it is a statement, not a Function) to read and transfer files from one folder to a different location on the disk.  The files can be of any type, like *.pdf, *.docx, Xls, or *.* (all files).

The files will be read and listed in a Listbox from the selected folder, specified in a text box.,  with the use of the DIR() Command.  All the files in the list or selected ones can be copied to a different location specified in a text box, defined as the target location.

The Utility Form.

The design view image of a Form created for this purpose is given below for reference:

The design is simple with two text boxes, one Listbox,  three Command Buttons, and a Label Control to display messages from this Utility Program.  You can download this Utility Form in a sample database at the end of this article.

These are the names of the Controls on the Form:

1. Top Text box: Source

2. Text Box 2:  Target

3. List Box:  List1

4. Top Command Button: cmdDir

5. Second Command Button : cmdSelected

6. Last Command Button : cmdClose

7. Bottom empty Label Name: msg

Note: If you are designing this form yourself, then ensure that you give the controls the same names as given above because the VBA code, that you are going to copy, and paste into the Module, will reference all these names in the Code. 

Besides the above main controls, there is a Label Control below the first Source Textbox showing examples as to how to specify Source File Path correctly.

The label control at the bottom of the form shows messages that pop up during validation checks of the inputs and when errors are detected, during the execution of the VBA Code.

An Image of a sample run of the FileCopy Statement is given below:

You may create this User Interface with the names of the Controls as given above.  After designing the form with the correct names for the controls, display the VBA Window of the Form, Copy and Paste the following code into the Form’s VBA Module:

The Form Module Code.

Option Compare Database
Option Explicit
Dim strSource1 As String
Dim strSource2 As String, strMsg As String

Private Sub cmdClose_Click()
On Error GoTo cmdClose_Click_Error

If MsgBox("Close File Copy Utility?", vbOKCancel + vbQuestion, "cmdClose_Click()") = vbOK Then
   DoCmd.Close acForm, Me.Name, acSaveYes
End If

cmdClose_Click_Exit:
Exit Sub

cmdClose_Click_Error:
MsgBox Err.Description, , "cmdClose_Click()"
Resume cmdClose_Click_Exit
End Sub

Private Sub cmdDir_Click()
'=========================================================
'Author : a.p.r.pillai
'Date   : June 2018
'Purpose: Take directory listing
'Rights : All Rights Reserved by www.msaccesstips.com
'=========================================================
Dim strSource As String, strMsg As String
Dim i As Integer, x As String
Dim j As Integer, strfile As String
Dim strList As ListBox, LList As String

On Error GoTo cmdDir_Click_Err
msg.Caption = ""

'Read Source location address
strSource = Nz(Me!Source, "")
If Len(strSource) = 0 Then
    strMsg = "Source Path is empty."
    MsgBox strMsg,vbOKOnly + vbCritical, "cmdDir_Click()"
msg.Caption = strMsg
    Exit Sub
End If

'check for the last back-slash location
'this can be used to split the folder name
'and file name type values separately.

i = InStrRev(strSource, "\")

'get the folder name part into the variable
strSource1 = Left(strSource, i)

'take file type (*.docx, *.exl, *.txt etc.) value into a separate
'variable temporarily
If Len(strSource) > i Then
    strSource2 = Right(strSource, Len(strSource) - i)
End If

'define Listbox object
Set strList = Me.List1

'Read the first file from the folder
strfile = Dir(strSource, vbHidden)
If Len(strfile) = 0 Then
    strMsg = "No Files of the specified type: '" & strSource2 & "' in this folder."
    MsgBox strMsg, vbCritical + vbOKOnly, "cmdDir()"
    msg.Caption = strMsg
    Exit Sub
End If

j = 0
LList = ""
Do While Len(strfile) > 0
   If Left(strfile, 1) = "~" Then 'ignore backup files, if any
      GoTo readnext:
   End If
    j = j + 1 'File list count
    LList = LList & Chr(34) & strfile & Chr(34) & ","
    
readnext:
    strfile = Dir() ' read next file
Loop

LList = Left(LList, Len(LList) - 1) ' remove the extra comma at the end of the list
strList.RowSource = LList 'insert the files list into the listbox RowSource property
strList.Requery 'refresh the listbox
msg.Caption = "Total: " & j & " Files found."

Me.Target.Enabled = True

cmdDir_Click_Exit:
Exit Sub

cmdDir_Click_Err:
MsgBox Err.Description, , "cmdDir_Click()"
Resume cmdDir_Click_Exit

End Sub


Private Sub cmdSelected_Click()
'=========================================================
'Author : a.p.r.pillai
'Date   : June 2018
'Purpose: Copy Selected/All Files to Target Location
'Rights : All Rights Reserved by www.msaccesstips.com
'=========================================================

Dim lstBox As ListBox, ListCount As Integer
Dim strfile As String, j As Integer, t As Double
Dim strTarget As String, strTarget2 As String
Dim chk As String, i As Integer, yn As Integer
Dim k As Integer

On Error GoTo cmdSelected_Click_Err

msg.Caption = ""
'Read Target location address
strTarget = Trim(Nz(Me!Target, ""))

'validate Destination location
If Len(strTarget) = 0 Then
   strMsg = "Enter a Valid Path for Destination!"
   MsgBox strMsg, vbOKOnly + vbCritical, "cmdSelected()"
   msg.Caption = strMsg
   Exit Sub
ElseIf Right(strTarget, 1) <> "\" Then
      strMsg = "Correct the Path as '" & Trim(Me.Target) & "\' and Re-try"
      MsgBox strMsg, vbOKOnly + vbCritical, "cmdSelected()"
      msg.Caption = strMsg
      Exit Sub
End If

'Take a count of files in listbox
Set lstBox = Me.List1
ListCount = lstBox.ListCount - 1

'take a count of selected files, if any, for copying
i = 0
For j = 0 To ListCount
If lstBox.Selected(j) Then
  i = i + 1
End If
Next

'identify user's response for copy
If (i = 0) And (ListCount > 0) Then
       strMsg = "Copy all Files..?"
       Me.cmdSelected.Caption = "Copy All"
Else
       strMsg = "Copy Selected Files..?"
       Me.cmdSelected.Caption = "Copy Marked files"

End If

'Me.cmdSelected.Requery

'get copy option from User
yn = MsgBox(strMsg, vbOKCancel + vbQuestion, "cmdSelected_Click()")

'Run Copy selected option
If (i = 0) And (yn = vbOK) Then
    GoSub allCopy
ElseIf (i > 0) And (yn = vbOK) Then
    GoSub selectCopy
Else
    Exit Sub
End If

'disable Copy button to stop a repeat copy of the same files.
'Remarks: User can make fresh selections from the same list
'To copy them to the same target locatiion.
'Or to a different location by specifying different Path
'in the Destination Text Box
Me.List1.SetFocus
Me.cmdSelected.Enabled = False

'Display copy status
strMsg = "Total " & k & " File(s) Copied." & vbCrLf & "Check the Target Folder for accuracy."
MsgBox strMsg, vbInformation + vbOKOnly, "cmdSelected_Click()"
Me.msg.Caption = strMsg

cmdSelected_Click_Exit:
Exit Sub

allCopy:
k = 0
For j = 0 To ListCount
    strfile = lstBox.ItemData(j)
   
    strSource2 = strSource1 & strfile
    strTarget2 = strTarget & strfile
    
    FileCopy strSource2, strTarget2
  'give enough time to copy the file
  'before taking the next file
  k = k + 1
  t = Timer()
  Do While Timer() > (t + 10)
    'do nothing
  Loop
Next
Return

selectCopy:
k = 0
For j = 0 To ListCount
   If lstBox.Selected(j) Then
        strfile = lstBox.ItemData(j)
        strSource2 = strSource1 & strfile
        strTarget2 = strTarget & strfile
        
            FileCopy strSource2, strTarget2
               'give enough time to copy the file
               'before taking the next file
               k = k + 1
                t = Timer()
                Do While Timer() > (t + 10)
                    'do nothing
                Loop
   End If
Next
Return


cmdSelected_Click_Err:
MsgBox Err.Description, , "cmdSelected_Click()"
Me.msg.Caption = Err.Description
Resume cmdSelected_Click_Exit

End Sub


Private Sub List1_AfterUpdate()
On Error GoTo List1_AfterUpdate_Error
Me.cmdSelected.Enabled = True
List1_AfterUpdate_Exit:
Exit Sub

List1_AfterUpdate_Error:
MsgBox Err.Description, , "List1_AfterUpdate()"
Resume List1_AfterUpdate_Exit
End Sub

You may save the Form with the name FileCopy.

Note: FileCopy is a VBA Statement, not a built-in Function.

You may copy different sets of files from the list of files displayed in the List Box to different Target Folders by selecting the files (after de-selecting earlier selections) and after changing the Destination Location address in the Text Control.

Download the Demo Database.

You may download the sample database with the VBA Code from the Link given below:

Download FileCopy2007.zip
Download (2003) FileCopy.zip

• Disk Operating System Commands in VBA
• Saving Report Pages as Separate PDF Files
• How to Use Form Filter on Report
• Back-tracking Open Forms

Read More

DIR Getting File Names From Folder

Introduction.

We all know Dir() Function from the time of the Windows DOS Operating System.  This is the first Command introduced to those who sit on a Personal Computer to learn how to use Computers.  This command has several options, to get the output from the disk in so many ways, under Windows Operating System.  You can take a full list of Folders, Subfolders, and Files from the hard disk in a single command.  The entire list can be sent to a Printer or saved into a text file with the use of the redirection symbol (>).

We are not going to use all those options here.  We will see how Dir() Function is used in VBA to read file names from a folder one by one and display them in the Debug Window.  Every time we run this function with a Folder Path as a parameter, it returns the first file name from the folder.  Now, the question is how to get the next few file names or all the files one-by-one from the Folder.

Using DIR Command in Debug Window.

We will try Dir() Function from the Debug Window directly so that it is easy to understand how to use this function to get a few file names from a folder one after the other.

1. Open Microsoft Access VBA Window and then display Debug Window (Ctrl+G).
2. Type the following command in the Debug Window and press Enter Key:

   ? Dir("")

   Dir() Function with an empty string as a parameter will fetch the first file name from the Current Folder and display it in the debug window. 

   Since we have not given any specific folder name in the function parameter, it looks for files in the active folder on the disk.

3. Now, issue the following command without any parameter to get the next file name in the current folder

   ? Dir()
   OR
   ? Dir

4. Each time you run the DIR() command it will get the next file from the folder.
5. Use a specific Folder Path as the parameter, in place of the empty string to get files from that particular folder.
6. Example:

   ? Dir("D:\Documents\")
   OR
   ? Dir("D:\Documents\*.*")
   

If D:\Documents\ folder doesn't have any files in it then the above command will return an empty string. If you go further and execute the Dir command again, then it will end up with an error message.

There is an optional second parameter to the Dir() Command that we have not used in the above examples. Since this is a DOS Command executed in its own window we can specify this second parameter to show its normal window(vbNormal) or hide the execution window (vbHidden) among other options available.

A VBA Wrapper Function for DIR Function.

I have written a small function for you to list all the files in a folder in the Debug Window.

Public Function TestDir(ByVal strFolder As String) As String
'Function Usage e.g.: TestDir "D:\Documents\"
Dim j As Integer, strFile As String
'files counter
j = 1
'Run the function with the specified folder in a hidden window
strFile = Dir(strFolder, vbHidden)
'Next steps of Dir() function is nested in a loop
'to read all the files and print in the Debug Window

Do While Len(strFile) > 0
 Debug.Print j & ":" & strFile
 j = j + 1
 strFile = Dir()
Loop
End Function

Call the function from the Debug Window by giving the full path of the Folder as the parameter.

? TestDir("D:\Documents\")
OR
? TestDir("D:\Documents\*.*")

All the files from the specified folder will be printed with a serial number in the debug window. After reading and printing the last file from the folder the Dir() function executes one more time and ends up with an empty string. The Do While condition will prove false and the program stops.

If you need only a specific type of File only to be read and display, then you may specify the parameter with the file type extension.

Example:

? TestDir("D:\Documents\*.xls")

The above example will read-only Excel files and print in the Debug window.

I have used the term Function and Command interchangeably. Dir() is referred to as a Function in VBA reference documents and as Command in Disk Operating System documents, both refer to the same operations done in different environments.

• Disk Operating System Commands in VBA
• Microsoft DOS Command in VBA
• Microsoft DOS Command in VBA-2
• ChDir and IN Clause of Access Query
• Deleting Folders with DOS Command

Read More

Unsecured Database and Users Log

Introduction

When Data Entry or Editing actions are performed on important Tables in Databases a TimeStamp with User Name is normally saved in each record to mark that event. This is done through the Form Before Update Event Procedure. A sample procedure is given below:

Private Sub Form_BeforeUpdate(Cancel As Integer)
     Me![EditedBy] = CurrentUser
     Me![EditedDt] = Now
End Sub

These fields will be added to the Data Entry/Editing Form from the Table but will be kept hidden or disabled to prevent manual changes. The familiar function =Now() gives the Date/Time Stamp value and the Current User built-in function provides the User Name, from the current instance of the database opened in the Workstation. We are focusing on the usage of the CurrentUser() method.

The CurrentUser function can return the User Name value correctly from a secured database (from a database that is implemented with Microsoft Access Security features) shared on a Network. When each authorized User attempts to open an instance of the database in her Workstation she has to provide her authenticated User Name and Password before getting access to the database or its other Objects. Consequently, the values returned by the CurrentUser() Function will always point to the correct User.

The Admin User.

But, if the database is not implemented with Microsoft Access Security then the CurrentUser() function will always return the value Admin. Any user who opens an Unsecured Database in a network will be silently logged in by MS-Access as Admin User, as a member of the Admins Group Account, and will never prompt for any User Name or Password.

We are not going to explore the Microsoft Access Security issues involved here (I have already dedicated about nineteen Pages on this issue under the Microsoft Access Security topic on the Main Menu of this Site) but how to get the Network User Name and the Workstation Name correctly if we want to record those values, in an unsecured database shared on a Network?

Yes, there is a simple Trick that you can use to capture their Network User Names and Workstation IDs and record those values in the Table fields. No, we don't need any lengthy VBA program to do this. But, first, let us see from where we will get this information. We will try to find your own Network User ID and Workstation ID stored in your computer's memory.

Finding Computer Name

1. Select Run from Start Menu.
2. Type Cmd and click OK. A DOS window will open up.
3. Type SET and press the ENTER key.

A lengthy list of Environmental Values is displayed in the DOS (Disk Operating System, the main driving force behind the Windows Operating System) Window. These are loaded into memory when you turn on the Computer or after Logoff/Logon actions and influence the smooth running of your data-to-day tasks. We are interested in only two values among them and look for the following Values:

COMPUTERNAME=your Computer Name

USERNAME=your Network User ID

These may not be in the nearby lines in the Environment Settings but can appear anywhere within the list, if necessary, use the Scroll Bar to move the list up or down, when you are sure you have spotted these values then type Exit and press the ENTER key to come out of the DOS window.

There is a built-in function ENVIRON() in MS-Access that we can use to capture these values from Memory and use it where we want them in our Database.

Example-1: X = ENVIRON("USERNAME")

This will bring the Network User ID of the User from memory.

Example-2: X = ENVIRON("COMPUTERNAME")

This will get the WorkstationId (Computer Name) from the Environment String that we have seen in Memory.

In fact, we can write two simple Functions with the Environ() Function and add them to our own Function Library in the Global Module. This will simplify the usage of this Function and we will only need to use the Function Name that we have defined, like Current User, to get these values from memory.

Since CurrentUser is a built-in function we will use something different that we can memorize easily. We can even use the Parameter Values of Environ() function as our own function names.

Add the following Functions in the Global Module (Standard Module) of your Function Library Database or in the shared database itself:

Public Function UserName() As String
    UserName = Environ("UserName")
End Function

Public Function ComputerName() As String
    ComputerName = Environ("ComputerName")
End Function

After adding these Functions to the Global Module you can call them from wherever you want, like:

Private Sub Form_BeforeUpdate(Cancel As Integer)
On Error Resume Next
      If Err then
        Cancel = True
      Else
       Me![EditedBy] = UserName
       Me![EditedDt] = Now
      End IF
End Sub

OR

If Msgbox("Hi, " & UserName & ", Shutdown Application..?", vbQuestion+vbDefaultButton2+vbYesNo,"Shut Down")=vbYes then
     docmd.Quit acQuitSaveAll
End If 

Similarly, the ComputerName() Function will get the Workstation ID of the User from Memory.

Monitoring Intrusions

These are also useful to monitor unauthorized use of third parties, or somebody not entrusted to maintain the open database,  from the Network Drive, by sending an Alert Message to you from the Startup Screen or Main Switch Board Form's Open Event Procedure like the example given below:

Private Sub Form_Open(Cancel As Integer)
       Call Shell("NET SEND YourNetworkID from: " & ComputerName & " User: " & UserName & " opened: " & Currentdb.Name & " at: " & Now())
End Sub

Note: NET SEND was Windows XP Command, its new Version is MSG Command.

Refer to the following Posts for more advanced techniques:

1. Record the Open/Close events, and activity of Databases in a log Text File and send alerts to your machine in a popup message box, which you can turn on or off as you need them.

   Database Open/Close Event Alerts.

2. Sending Alerts to other User Workstations with useful information that they need to know about, immediately after processing activities take place on one side of the User Groups.

   Sending Alerts to Workstations.

3. How many users are currently online with a particular database and how to communicate with them by sending Alerts to their Workstations?

   Who is online?

4. Send E-Mails to remote Users with attachments of important Reports in Snapshot Format.

   Automated E-Mail Alerts

Earlier Post Link References:

• Form Background with Gradient Color
• MS-Access and Reference Library
• InputBox and Simple Menus
• Change Form Modes On User Profile
• Positioning POPUP Forms

Read More

Cardinal Text Format In Access

Introduction

The other day one of my colleagues asked me to open MS Word and type the expression =Rand() on a separate line and press the Enter key. It was magic that I didn't know till that time. The following sentence appears fifteen times repeatedly (in 3 rows and 5 columns) overwriting the expression itself:

The quick brown fox jumps over the lazy dog.

Open a Document in MS Word and try it out yourself. The above sentence has all the letters of the alphabet in it. You can control the printing, by inputting parameters to the Function like =Rand(5,1) will print the same sentence in 5 lines in one Column. It is a built-in Function with different constructs that can accept a different set of parameters and looks like created for fun, I think! It works only when you type it on a separate line. Even though it looks like a Random Function it has nothing to do with it.

There is another feature in MS-Word that, I like to see in MS-Access, formats numeric values in Cardinal Text Format.

For example, the result of the Mail Merge formula { = 9.20 + 5.35 \* CardText } outputs fourteen and 55/100, when the document is merged into another Document or to Printer. Format switches can be either \* DollarText or \* CardText to get the above output. When the \* Caps switch is added to it, like { = 9.20 + 5.35 \* DollarText \* Caps} , then it changes the first letter of each word in upper case.

This is very useful for printing Invoice values in MS-Access. I have written a Function to achieve this in MS-Access and here it is for you to try it out.

The CardText() Function

Copy and Paste the following Code into a Global Module of your Database and save it:

Public Function CardText(ByVal inNumber As Double, Optional ByVal precision As Integer = 2) As String
'------------------------------------------------------------------------
'Author : a.p.r. pillai
'Date   : December 2008
'URL    : www.msaccesstips.com
'All Rights Reserved by www.msaccesstips.com
'------------------------------------------------------------------------
Dim ctu, ctt, bmth
Dim strNum As String, j As Integer, k As Integer, fmt As String
Dim h As Integer, xten As Integer, yten As Integer
Dim cardseg(1 To 4) As String, txt As String, d As String, txt2 As String
Dim locn As Integer, xfract As String, xhundred As String
Dim xctu As String, xctt As String, xbmth As String

On Error GoTo CardText_Err

strNum = Trim(Str(inNumber))
locn = InStr(1, strNum, ".")
'Check Decimal Places and rounding
If locn > 0 Then
  xfract = Mid(strNum, locn + 1)
 strNum = Left(strNum, locn - 1)
    If precision > 0 Then
        If Len(xfract) < precision Then 
        	xfract = xfract & String((precision - Len(xfract)), chr(48))
        ElseIf Len(xfract) > precision Then
            xfract = Format(Int(Val(Left(xfract, precision + 1)) / 10 + 0.5), String(precision, "0"))
        End If
        xfract = IIf(Val(xfract) > 0, xfract & "/" & 10 ^ precision, "")
    Else
        strNum = Val(strNum) + Int(Val("." & xfract) + 0.5)
        xfract = ""
    End If
End If

h = Len(strNum)
If h > 12 Then
'if more than 12 digits take only 12 (max. 999 Billion)
'extra value will get truncated from left.
   strNum = Right(strNum, 12)
Else
   strNum = String(12 - h, "0") & strNum
End If

GoSub initSection

txt2 = ""
For j = 1 To 4
    If Val(cardseg(j)) = 0 Then
       GoTo NextStep
    End If
    txt = ""
    For k = 3 To 1 Step -1
      Select Case k
       Case 3
            xten = Val(Mid(cardseg(j), k - 1, 1))
            If xten = 1 Then
                txt = ctu(10 + Val(Mid(cardseg(j), k, 1)))
            Else
                txt = ctt(xten) & ctu(Val(Mid(cardseg(j), k, 1)))
            End If
        Case 1
            yten = Val(Mid(cardseg(j), k, 1))
            xhundred = ctu(yten) & IIf(yten > 0, bmth(1), "") & txt
            Select Case j
                Case 2
                      d = bmth(2)
                Case 3
                    d = bmth(3)
                Case 4
                    d = bmth(4)
            End Select
            txt2 = xhundred & d & txt2
    End Select
   Next
NextStep:
Next

If Len(txt2) = 0 And Len(xfract) > 0 Then
    txt2 = xfract & " only. "
ElseIf Len(txt2) = 0 And Len(xfract) = 0 Then
    txt2 = ""
Else
  txt2 = txt2 & IIf(Len(xfract) > 0, " and " & xfract, "") & " only."
End If

CardText = txt2

CardText_Exit:
Exit Function

initSection:
xctu = ", One, Two, Three, Four, Five, Six, Seven, Eight, Nine, Ten, Eleven, Twelve,"
xctu = xctu & " Thirteen, Fourteen, Fifteen, Sixteen, Seventeen, Eighteen, Nineteen"
ctu = Split(xctu, ",")

xctt = ", Ten, Twenty, Thirty, Fourty, Fifty, Sixty, Seventy, Eighty, Ninety"
ctt = Split(xctt, ",")

xbmth = ", Hundred, Thousand, Million, Billion"
bmth = Split(xbmth, ",")
k = 4
For j = 1 To 10 Step 3
    cardseg(k) = Mid(strNum, j, 3)
    k = k - 1
Next
Return

CardText_Err:
CardText = ""
MsgBox Err.Description, , "CardText()"
Resume CardText_Exit
End Function

The CardText() or the DollarText.

Sample Demo Runs

The Function name CardText() is derived from MS Word Number Format Switch \* CardText. The CardText() Function accepts a maximum value of 10^12-1 or up to 999 Billion. For most applications, this will be sufficient. Passing a Value greater than this will get truncated from the left.

The CardText() Function accepts two parameters and the second one is optional. The second parameter controls the number of digits after decimal places.

By default, the CardText() Function will round off the fractional part, if present, to two decimal places when the second parameter value is omitted.

To try out the Code you may open VBA Window (Alt+F11) and open the Immediate Window (Ctrl+G) and type the following statement or similar one with a different value or Expression:

Example:? CardText(1234.5678,3) will produce the result shown below.

Result: One Thousand Two Hundred Thirty-Four and 568/1000 only.

The first parameter can be a Number or an Expression that evaluates to a Numeric Value. If the second parameter is zero then the Number is rounded to the next highest Integer.

Example: ? CardText(1234.5678,0)

Result: Thousand Two Hundred Thirty-Five only.

To change the output to upper-case or lower-cases letters enclose the CardText() Function in UCase() or LCase() built-in function respectively.

Example: ? UCase(CardText(1234.5678))

Result: ONE THOUSAND TWO HUNDRED THIRTY-FOUR AND 57/100 ONLY.

To prefix a Currency Description use the following example:

Example: ? "Dollars" & CardText(1234.5678)

Or

="Dollars" & CardText([UnitPrice]) on Forms  or  Reports.

Result: Dollars One Thousand Two Hundred Thirty-Four and 57/100 only.

You may try the Function on Form or Report with the data field Value as input.

The CardText() Function is not extensively field-tested and if you find bugs please let me know. Use it at your own risk.

Any suggestions for improvement are welcome.

CardTextV2.zip

• Seriality Control - Missing Numbers
• Wave Shaped Reminder Ticker
• No Data and Report Error
• Lost Links of External Tables
• Link External Tables with VBA

Read More