Week 10

Protecting Code Protecting Worksheets Error Handling Charts

Using form tools Changing the QAT Revision Exercises

Run the Add Customer form from the button on the Data Sheet

Features:• Auto number Customer

ID• Accommodates other

ranges in the worksheet

Design Issues:

• Uses Named Range to place details on the sheet

• Code attached to Initialize event generates an autonumber

• The text box’s Enabled property is set to False to disallow editing

• Need to update the named range after input

• some data below the named range which we don’t want to overwrite

Locking the project for viewing means that the macros will still run but that users will need a password to access the code in the editor.

Close the file and reopen it. To access the code of a

protected project, from the Project Window, double click on the appropriate project and enter the password at the prompt.

You can password protect sheets using the Review tab in excel where you can specify the limits of the protection

You can exclude selected cells from the protection by highlighting and using the protect cells tab of the format cells dialog

A line of code to protect the current sheet might look like this.

ActiveSheet.Protect "password" True, True, True

Where ActiveSheet is the object and Protect the method.

Protect has many arguments. The first is the password string, followed by

a series of True/False arguments resembling the tickbox list found in Excel.

As with the Excel interface, by default most options are set to True (protected) whilst a few are false (unprotected)

Instead of always protecting the active sheet, you might want the user to choose which sheet to unprotect

Sub protect_choose()

Dim mySheet As WorksheetDim sheetName As String

sheetName = InputBox("Please type Sheet name", "non-robust sheet selector", "sheet1")

Set mySheet = Worksheets(sheetName) mySheet.protect “password"End Sub

Adapt previous macro to protect each sheet in turn

Sub ProtectSheets()  Dim mySheet As Worksheet mySheet.Protect “password"End Sub

If you try to run a sub to add a worksheet named “Results” where a worksheet named “Results” already exisits,• Sub will stop running• A message box containing an error code will

appearError handling seeks to write code that deals

with the issue and moves on to the next line

Use On Error Resume Next to allow the macro to continue when an error is encountered.

Use Err.Number to find out if there is an error or not. If the number property of the Err object is 0, then no error occurred. For example:

If err.number <> 0 Then -- do something to cope with

eventuality --End if

Function SheetExists• This function uses the Err object to see if an

error occurs when a sheet is referenced, i.e. it doesn’t exist. If an error occurs, then the Resume command clears the error and allows the program to continue.

• Can be used within another sub to check for a sheet name before trying to use the name for another sheet

Sub make_report()

Dim mysheet As WorksheetDim myBase As StringDim mySuffix As IntegerSet mysheet = Worksheets.Add

myBase = "Report"mySuffix = 1

On Error Resume Nextmysheet.Name = myBase & mySuffix

Do Until Err.Number = 0 Err.Number = 0 mySuffix = mySuffix + 1 mysheet.Name = myBase & mySuffixLoop

End Sub

Record a macro to create a chart (start with a simple column chart) in a new sheet for the exam results on the exams sheet

Good example of instance where recorded code and reference to the object map can help

 Sub MakeChart()  Selection.CurrentRegion.Select Charts.Add ActiveChart.ChartType = xlColumnClustered ActiveChart.SetSourceData

Source:=Sheets("Exams").Range("A1:B10")_, PlotBy:= xlColumns

ActiveChart.Location Where:=xlLocationAsObject, Name:="Exams" With ActiveChart .HasTitle = True .ChartTitle.Characters.Text = "Exam Marks" .Axes(xlCategory, xlPrimary).HasTitle = False .Axes(xlValue, xlPrimary).HasTitle = False End With

ActiveChart.HasLegend = FalseEnd Sub 

Adapt your code to produce a pie chart

Rename the chart Label the axis Allow the user to select the range of

the chart data

Module level variables

• Use module level variables only when two or more subs need access to the same variable; otherwise it’s better practice to use variables local to the procedure they are in.

• To declare a module level variable, you declare it in the Declarations section (where the Option statements are), before any subs.

You can use Dim as previously, but it is recommended you use the keywords Private or Public to determine the scope of the variable. Private variables are accessible only to the subs in the same module, Public variables are accessible to all the subs in the workbook.

An example of a longer application Uses Module level variables Has three main Subs which call on

combinations or smaller subs Uses Workbook_Open event handler

to reset workbook