VBA Training Presentation

VBA Training

CONFIDENTIAL AND PROPRIETARY INFORMATION

This presentation and the information contained herein are confidential and proprietary,and are intended for review only by the employees of marketRx, Inc. All other reviewers must have the prior written consent of marketRx, Inc.

Copyright © 2005 marketRx, Inc. All rights reserved.


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Agenda

Examples of all Excel functions and VBA code from this presentation can be found in the excel supplement

Visual Basic for Applications (VBA)

Visual Basic for Applications – Excel Objects

Visual Basic for Applications – Database Connectivity

Microsoft PowerPoint


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A macro is a short program written using VBA that can be used to carry out a specific task

VBA is the language that Excel macros are written in. It is a programming language that is included with all of the Microsoft Office applications e.g. Word, Access, PowerPoint, Excel as well as others. VBA is a subset of Microsoft Visual Basic, an extremely popular programming

language that has been around for over 10 years.


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VBA

VBA=General Programming + Object Manipulation

Excel Object Model

Excel VBA Applications

General Programming

Concepts


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Create Your First Macro - Step 1

Open Visual Basic Editor by go to Tools...Macro...Visual Basic Editor or just simply press the [Alt] and [F11] keys at the same time.


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In the Insert menu on top of the Visual Basic Editor, select Module to open the Module window (code window).


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In the Module window, type the following:

Sub showMessage() MsgBox "Hello World!"End Sub


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Run Your First Macro

Click the Run button, , press [F5], or go to Run..Run Sub/UserForm to run the program

The message box pops up with the "Hello World!" greeting.


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Macro Security Levels / Virus Protection

Security levels – control how Excel handles suspect macros. High: causes Excel to disable all

macros either lacking a digital signature or containing an invalid one.

Medium: Excel prompts the user to enable the macro or not if it lacks a digital signature. Certificates with invalid signatures are automatically disabled. Macros containing a valid signature are automatically enabled.

Low: All macros are enabled.

Macros without a digital signature are disabled by default in Excel 2000.

To enable macros, go to “Tools Options Macro Security” and then select “medium”.


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The Macro Dialog Box

The following figure is an example of the Macro dialog box. In this dialog box, three macros have been created.

To run a macro, you select the macro you want from the list and press the Run button.


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Visual Basic Editor


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Project Explorer in Visual Basic Editor

The Project Explorer is the window you can see to the left of the above screenshot (the one that shows you the two VBAProject items).

This will list each file that you have open including any Excel add-ins and hidden workbooks. In VBA terms each file is referred to as a project.

Expand the Format Sales Report Macro project by clicking on the + sign next to it and ensure anything underneath it is also expanded.


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Properties in Visual Basic Editor

Change module name

Properties panel


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Three Ways to Run Macros

Tools Macro Macros

Put a button on the worksheet Note that when you create the button a macro assignment dialog opens

automatically

Put a button on a toolbar Right-click on a toolbar, then Customize Commands Macro


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Assigning a Macro to a Button on a Worksheet

Form Toolbar Button created

Assign macro to the button


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Assigning a Macro to a Button on a Worksheet

Add a Button in an Excel sheet Display the Forms toolbar. Click the Button icon. Click and drag the mouse pointer to specify the position and size of button. Select the macro name you are assigning to this button from the Assign Macro

dialog box. Click OK.

Change the Name of the Button Highlight the button (Hit Ctrl and click on the button). Highlight the label on the button. Type a new name for the button. Click outside the button.

Click the button will run the linked macro.


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The Forms toolbar

In this figure, you see the Forms toolbar. Notice the button tool on the right side of the toolbar. This button tool will

create a command button on your worksheet.


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VB Stuff You Must Learn Quickly

Declaring functions and subroutines

Declaring variables

Assigning values to variables and doing calculations

Conditional Logic: If..Then..Else

Iteration: Do..Loop, For..Next

Simple communication with user via InputBox() and MsgBox() functions

Logically designing programs consisting of multiple procedures working together to accomplish some task


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Subroutines and Functions Subroutines

Sequence of commands DOESN’T return a value Takes any number of arguments

Functions Generally an algorithm or computation Takes any number of arguments Often returns one value, but can create array functions for many outputs


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Writing Functions

You can write a function in VBA that can be called by a formula from an Excel worksheet

Example:

Whatever you define the function as, that is how you call it from an Excel worksheet

This function takes one argument, the value to be cubed. The value to be returned from the function must be set equal to the name of the function

Example of how to call this function from an Excel worksheet: =Cubic(A1) Where A1 is the cell where the number to be cubed is located


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Add a New Procedure/Function Through Wizard

Give it a name

What kind of procedure?

Who can “see” the procedure?


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Passing Argument by Reference or by Value

If you pass an argument by reference when calling a procedure, the procedure access to the actual variable in memory. As a result, the variable's value can be changed by the procedure.

Passing by reference is the default in VBA. If you do not explicitly specify to pass an argurment by value, VBA will pass it by reference. The following two statements yield the same outcome.

Sub AddNo(ByRef x as integer)Sub AddNo(x as integer)

Here is an example to show the by reference behavior. The sub procedure, TestPassing 1 calls AddNo1 by reference and display "60" (50 + 10) on the message box.

The following example shows the by value behavior. The sub procedure, TestPassing 2 calls AddNo2 by value and display "50" on the message box.

Sub TestPassing1()Dim y As Integery = 50AddNo1 yMsgBox y

End Sub

Sub AddNo1(ByRef x As Integer)x = x + 10

End Sub

Sub TestPassing2()Dim y As Integery = 50AddNo2 yMsgBox y

End Sub

Sub AddNo2(ByVal x As Integer)x = x + 10

End Sub


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Variables

Variables are used for temporary storage of values

Declare variables with Dim You have to state the variables data type The declaration have to be made before using the variable Example: Dim NumItems As Integer

Variables do not have to be defined in VBA, but it is good programming practice to define them To force the definition of variables, at the top of the module window type the

following:• Option Explicit

To force Option Explicit for all Modules: Tools Options Check “Require Variable Declaration”


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Common Data Types

String – for text like “Bob Smith” string literals are enclosed in quotes

Integer – integers in –32768 to 32768 Long – for bigger integers Boolean – only True (-1) or False (0) Double – numbers with decimals Currency – monetary values Date – for dates and times

date literals must be like this: #1/7/2005# Object – specific versions for each object type Variant – let VBA decide how to deal with

If you don’t declare a variable, this is the default data type VBA will use. This should be avoided as much as possible.


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You Should Declare Variables Yourself

They take up less memory

The code runs smoother

The code is easier to read

VBA checks for misspelled variable names

You cannot put the wrong data type into a variable

It’s good programming style


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Building Blocks of Expressions

Relational LogicalOperator Description Operator= Equal And<> Non equal Or< Less than Not> Greater than<= Less than or equal to Literals Example

>= Greater than or equal to Value 23Arithmetic Operator Description

Text or String "Smith"

+ - / * ^add, sub, div, mult, power Date #1/1/2000#

& string concatentation Yes/No -1=TRUE=Yes0=FALSE=No

(1) Relational and Arithmetic Operators

(2) Logical Operators


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Visual Basic for Applications – Decisions

If…Then…Else Statements can be used in VBA

Msgbox(“string”) This will cause a Message Box to appear when the code is run


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Visual Basic for Applications – Select Case

Select Case statement is an alternative to the ElseIf statement. This method is more efficient and readable in coding than the “If ... Then ... ElseIf” statement.

Example:

Select Case Grade Case Is >= 90 LetterGrade = "A" Case Is >= 80 LetterGrade = "B" Case Is >= 70 LetterGrade = "C" Case Is >= 60 LetterGrade = "D" Case Else LetterGrade = "Sorry" End Select


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Visual Basic for Applications – Loops

For…Next Loops For loops will repeat a block of code for a specified number of times

Changing increment size in the for loop

To exit the loop early “Exit For”


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Visual Basic for Applications – Loops

Do …Loop Loops -- Repeats statements while a condition is true Check condition prior to entering loop

Check condition after running through the loop once – Loop will always run at least once


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Arrays

A variable containing a list of values of the same data type. Values are accessed with variable name and an index.

Before signing values to an array, the array needs to be created. You can declare the array by using the Dim statement.

To declare a one-dimensional array with 5 elements, type the following:

Dim Arr(5) as string

The element’s index of the array starts from 0 unless Option Base 1 is specified in the public area (area outside of the sub procedure).

You can also define the array to start from any base number, for example, dim arr(2 to 6) will define a 5-element array with index starting from 2.


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Dynamic Arrays

The ReDim statement is used to size or resize a dynamic array that has already been formally declared. For example, if you have already declared an array with an element value of 5 and decided to change

the number of the element to 6, you can do the following to resize the array: Redim Arr(6)

ReDim cannot change the type of the array and it can only change the bounds of the array but not the number of its dimensions.

Each time you execute the ReDim statement, all the values currently stored in the array are lost, unless you use “Preserve” keyword, e.g. ReDim Preserve Arr(10).

The size of an array can be determined by the value of a variable – The following code is an example of that:


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Multi-Dimensional Array

An array can also store multiple dimensional data. To simplify our tutorial, example on a two-dimensional array is used.

Assume you have data of a local store's yearly sale in the following table and you want to store the data in a two-dimensional array:

Year 2003 Year 2004 CD Sale 1,000 1,500 DVD Sale 1,200 2,000

First we create the array as follow: Dim Arr(2,2) as long

Then we assign the values into the array. We treat the first dimension as the year and the second dimension as the product sale:

arr(1,1) = 1000 arr(1,2) = 1200 arr(2,1) = 1500 arr(2,2) = 2000


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Size of an Array

The largest available subscript for the indicated dimension of an array can be obtained by using the Ubound function.

UBound returns the following values for an array with these dimensions: Dim A(1 To 100, 0 To 3, -3 To 4)

Statement Return Value UBound(A, 1) 100 UBound(A, 2) 3 UBound(A, 3) 4

Use the LBound function to find the lower limit of an array dimension.

Statement Return Value LBound(A, 1) 1 LBound(A, 2) 0 LBound(A, 3) -3

To get the size of an array, use the following formula:

UBound(Arr) - LBound(Arr) + 1


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Useful String functions and other constructs

Left, Right, Mid – get parts of a string

Len – get the length of a string

Trim – get rid of trailing and leading spaces in a string

& - string concatenation operator

Val – converts string to number

Line continuation _

Comment ‘

There are a zillion useful built in functions in VBA. Learn how to find and use some of them.


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InputBox

InputBox – get a single value from the user Syntax: variable = InputBox(Prompt,Title)

Variable is a variable whose value is set based on user entry. Prompt is the message you want to appear in the input box. Title is the text that appears in the title bar of the input box.

Salary=InputBox(“Enter your salary.”, “Application”)


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Message Box

MsgBox – show user message, get button click response Syntax: MsgBox Prompt, Buttons, Title

Prompt is the message in the dialog box Buttons specifies the kind of buttons that appear in the message box, and the style of

the message box. Title is the text for the title bar

Examples: MsgBox “The macro is finished”, vbOKOnly, “Done” MsgBox “Proceed?”, vbOKCancel, “Start Macro”

MsgBox “The macro is finished”, vbOKOnly, “Done”


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Random Number

To generate random number from 0 to 1 uniformly, one can use the Rand() function in Excel or the Rnd function in VBA. These two functions are the mother of all

random numbers. You will need either one of these functions to generate random numbers from any probability distributions. Or you can use the random number generator in Analysis ToolPack Add-ins.

The rand() excel formula function before Excel 2003 has a low quality of randomness. The function was changed in Excel 2003 but has a bug. You need to download a fix from Microsoft. It is better to use Rnd() in VBA to generate random numbers for you.

The example on the right generates 5 random numbers and then displays them in a message box:

* CStr() function converts the random numbers into string.

Sub rndNo()Dim str As String

For i = 1 To 5str = str & CStr(Rnd) & vbCrLf

Next i

MsgBox strEnd Sub


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Randomize Statement

For the previous example, when we close the file, reopen it, and run the sub routine again, the same 5 numbers come up!

The reason why this happens is that the random numbers were actually being generated from the same set of numbers (called seed).

By placing the Randomize statement in the sub routine, the numbers will be generated from a new seed. (Randomize uses the return value from the Timer function as the new seed value.)

Sub rndNo()Dim str As String

RandomizeFor i = 1 To 5

str = str & CStr(Rnd) & vbCrLfNext i

MsgBox strEnd Sub


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VBA Debugging

Too many programmers become complacent once the code is written and they get a clean compile. These are only the first steps. The most important steps, and the ones programmers like the least, are debugging and testing code.

Three types of Errors Syntax errors: A variety of errors related to entering the code itself. These include

incorrectly spelled keywords, mismatched parentheses, etc. Excel flags your syntax errors and you can't execute your code until they are correct.

Run-time errors: These are the errors that occur while your code is executing. For example, if your code refers to an object that doesn't exist, you'll get a run-time error. Excel displays a message when there is a run-time error.

Logical errors: These are errors that occur through faulty programming. In many cases they will simply produce incorrect results.

Debugging your code is the process of finding and correcting run-time errors and logical errors

We will describe the various debugging resources available in the Visual Basic Editor (VBE) and how to use them. These are basic descriptions of the various diagnostic tools and how to use them. See

the on-line help for more details.


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Debug Message Box

The most common use of the debugger is to diagnose the code when a crash is encountered. If no error handling is in place, when an Access application crashes, you or your user are prompted with an End, Debug message box:


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Break Points

A break point is a setting on a line of code that tells VBA to pause execution immediately before that line of code is executed. Code execution is placed in what is called break mode. When a line contains a break point, it is displayed with a brick colored background. Immediately before this line of code is executed, it will appear with a yellow background.

When VBA is in break mode, you can enter commands in to the Immediate Window to display or change the values of variables.

To put a break point on a line of code, place the cursor on that line and press F9 or choose "Toggle Breakpoint" from the Debug menu.

To remove a break point, place the cursor on the line with the break point and press F9 or choose "Toggle Breakpoint" from the Debug menu.

After a break point is encountered, you can resume normal code execution by pressing F5 or choosing "Continue" from the Run menu, or stepping through the code line by line (see next slide).


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Break Mode


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Stepping Through Code

Normally, your code runs unattended. It executes until its logical end. However, when you are testing code, it is often useful to step through the code line by line, watching each line of code take effect. This makes it easy to determine exactly what line is causing incorrect behavior.

You can step through code line by line by pressing the F8 key to start the procedure in which the cursor is, or when VBA is paused at a break point.

Pressing F8 causes VBA to execute each line one at a time, highlighting the next line of code in yellow. Note, the highlighted line is the line of code that will execute when you press F8. It has not yet been executed.

If your procedure calls another procedure, pressing F8 will cause VBA to step inside that procedure and execute it line by line. You can use SHIFT+F8 to "Step Over" the procedure call. This means that the entire called procedure is executed as one line of code. This can make debugging simpler if you are confident that the problem does not lie within a called procedure.

When you are in a called procedure, you can use CTRL+SHIFT+F8 to "Step Out" of the current procedure. This causes VBA to execute until the end of the procedure is reached (an End Sub or Exit Sub statement) and then stop at the line of code immediately following the line which called the procedure.


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Stepping Through Code

VBA also supports "Run To Cursor". This is exactly what it sounds like. It tells VBA to execute code until the line on which the cursor is sitting is reached. When this line is reach, VBA enters break mode. This is similar to putting a break point on a line of code, except that the break point is

temporary. The second time that line of code is executed, code execution does not pause.

Set Next Statement [Ctrl+F9] This command lets you set the next statement as any line in the current procedure including lines you’ve already run. This is extremely powerful and quite amazing when you think about it. It’s particularly

useful if you run though some code and then decide you should repeat it because you missed something.

It’s not always the same as the first run because variables may have changed, but if you understand the situation, it lets you debug again without getting to the same code or situation again.

Show Next Statement Sometimes you examine different procedures as you debug your code, so the Show Next Statement menu command makes it easy to go to the currently highlighted line.


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Immediate Window

The Immediate Window is a window in the VBE in which you can enter commands and view and change the contents of variables while you code is in Break mode or when no macro code is executing. Break mode is the state of VBA when code execution is paused at a break point (see

Breakpoints, below.

To display the Immediate Window, press CTRL+G or choose it from the View menu.

In the Immediate Window, you can display the value of a variable by using the ? command. Simply type ? followed by the variable name and press Enter. VBA will display the contents of the variable in the Immediate Window. For example,

?ActiveCell.Address$A$10

You can also execute VBA commands in the Immediate Window by omitting the question mark and entering the command followed by the Enter key:

Application.EnableEvents=TrueorRange("A1").Value = 1234


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Locals Window

The Locals Window displays all the variables in a procedure (as well as global variables declared at the project or module level) and their values. This makes it easy to see exactly what

the value of each variable is, and where it changes, as you step through the code.

You can display the Locals Window by choosing it from the View menu. The Locals Window does not allow

you to change the values of variables. It simply displays their names and values.


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Watch Window

The Watch Window allows you to "watch" a specific variable or expression and cause code execution to pause and enter break mode when the value of that variable or expression is True (non-zero) or whenever that variable is changed.

To display the Watch Window, choose it from the View menu. To create a new watch, choose Add Watch from the Debug menu. This will display the Add Watch window, shown on the right.

Three watch types


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Writing Code for Debugging

You can use the Debug.Print statement anywhere in your code to display messages or variable values in the Immediate Window. These statements don't require any confirmation or acknowledgement from the user so they won't affect the operation of your code.

'' some code'Debug.Print "Starting Code Section 1"

In Excel 2000 and later, you can use Debug.Assert statements to cause the code to break if a condition is not met. The syntax for Debug.Assert is: Debug.Assert (condition) Example

Dim X As LongX = 123Debug.Assert (X < 100)


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Eight Bug Reduction Tips

You cannot completely eliminate bugs in your programs, but there are a few tips that will help you keep them to a minimum.

Use an Option Explicit at the beginning of your module. Doing so will require that you define the data type for every variable that you use. It's a bit more work, but you'll avoid the common error of misspelling a variable name.. And there's a nice side benefit: Your routines will often run faster.

Format your code with indentation. Using indentation to delineate code segments is quite helpful. If you have several nested For...Next loops, for example, consistent indentation will make it much easier to keep track of them all.

Be careful with On Error Resume Next. This statement causes Excel to ignore any errors and continue. In some cases, using this statement will cause Excel to ignore errors that shouldn't be ignored. Your may have bugs and not even realize it.

Use lots of comments. Nothing is more frustrating than revisiting code that you wrote six months ago - and not having a clue as to how it works. Adding a few comments to describe your logic can save you lots of time down the road.


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Eight Bug Reduction Tips

Keep your subroutines and functions simple. Writing your code in smaller modules, each of which has a single, well-defined purpose, makes it much easier to debug them.

Use the macro recorder to help you identify properties and methods. If I can't remember the name or syntax of a property or method, it's often quicker to simply record a macro and look at the recorded code.

Consider a different approach. If you're having trouble getting a particular routine to work correctly, you might want to scrap the idea and try something completely different. In most cases, Excel offers several alternative methods of accomplishing the same thing.

Understand Excel's debugger. Although it can be a bit daunting at first, you'll find that Excel's debugger is an excellent tool. Invest some time and get to know it.


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Agenda






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Excel and Objects

Excel (and the other Office applications) consists of a number of object. An object can be a cell, worksheet, or Excel application.

Macro programming is actually just manipulation of these objects.

When you understand the basic principle, it’s easier to learn how to program other Office programs.

Definition of an object An object is a named part of a computers memory. It has certain features or properties. Like some people have brown hair, others

red hair. It has some functionality or methods. Like people are able to walk or cars able to

drive. Objects can contain other objects.


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Properties of Objects

Properties- the attributes that distinguish an object. To change the property of an object, use the syntax in VBA:

object.property = expression Worksheets(“Grades”).Name = “Old Grades”

changes the Name property of the “Grades” worksheet to “Old Grades.”

Range(“G5”).Value = 880.55changes the Value property of cell G5 to 880.55.

Range(“H5”).Formula = “=G5-F4”changes the Formula property of cell H5 to =G5-F4

Worksheets(“Sheet 1”).Visible = Falsehides sheet 1. Change to True to make visible again.

Activecell.Value=15changes the value of the active cell to 15.

Activecell.parent.name will return the name of the worksheet that the active cell is on.


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Methods of Objects

A method is an action that can be performed on an object.

The syntax for applying a method is: object.method

Example: Sheets(“Table”).Delete will delete the Table sheet

Example: Range(“A1:B5”).Clear will clear the contents of A1:B5


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The Objects in Excel

The mother object is called ”Application”

Application contains a number of workbooks.

These workbooks contain sheets.

The sheets contain ranges etc.

Application, Workbooks etc contain many other objects, properties and method. Some objects can have properties that are

also objects.


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Accessing objects

To acces a certain sheet we would write:Application.Workbooks(”name.xls”).Sheets(”Name”)

We might not know the sheet name:Application.Workbooks(”name.xls”).Sheets(1)

We could now give that sheet a name: Application.Workbooks(”name.xls”).Sheets(1).Name _ = ”MyName”

All of these examples are Fully qualified references


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Implicit References

If a certain workbook is already active we could writeSheets(”theName”)

We could access a range in a sheet by writing:Sheets(”theName”).Range(”A1”)

Or to access a range in the active sheet:Range(”A1”)

If the range if a named range:Range(”RangeName”)


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Referencing Cells (Cont.)

Multiple ways to reference cells in VBA Cells(row_number, column_number)

• References a single cell Range(Cells(row_num_1, col_num_1), Cells(row_num_2, col_num_2))

• References multiple cells in the specified range Range(“Test_Range”)

• Can reference a “Named Range” of cells defined in the excel worksheet Named Ranges

Select the range of cells you want to reference

Name of Range Appears Here


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Referencing Cells

To access a range we could write:Range(”A1:B16”)

For the range stretching from A1 to B16. We could also write:Range(”A1”,”B16”)

If we would rather use column and row numbers. For the single cell range C2 we could write:

Cells(2,3)

We can access the range from A1 to B16 by:Range(Cells(1,1) ,Cells(16,2))


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Referencing Cells (Cont.)

Gathering Input from Cells Data in cells can be read into VBA and stored in a variable

test_var = Cells(1,1).Value Outputting to Cells

Data can be outputted into cells from VBACells(2,1) = 123456

Example:

Output


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Basic Range manipulation

The value of a range can be set and read with:Range(”A1”).Value = 123

The formula of a range can be set withRange(”A1”).Formula = ”=AVERAGE(A1:B16)”

Set the font of a Range:Range(”A1:B16”).Font.Bold = True

Set the color of a range:Range(”A1:B16”).Interior.ColorIndex = 3


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Formatting Cells

Recording Macros is very useful for learning the code to format cells a particular way Incorporate the code from the recorded macro into your code to assist in

formatting cells - eliminate any unnecessary steps excel has added in For example, to formats Cell “A1” to have a blue background and white

bold text, the following code is generated

Can be Reduced To

Same Result


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Deleting a Current Worksheet if it Exists Always set “DisplayAlerts” to False prior to deleting a worksheet so that the

code is not interrupted by a confirmation dialog box WksExists(Sheet_name) Calls another function that returns true if the Wks

Exists

Make sure to set “DisplayAlerts” back to True once the sheet is deleted Adding a new Worksheet

By defining a new variable as a worksheet, you will be able to easily rename it

Worksheet Functions


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Worksheet Functions (Cont.)

Looping Through Worksheets Useful if you want to perform a specific function to each sheet in the workbook

• Specific Formatting• Setting Column Widths• Protecting Cells – If you want to protect worksheets, always make sure you unprotect

the worksheets in the beginning of the code otherwise you will be asked for the password if you try to modify them. At the end of the code you can re-protect all of the worksheets

Example:


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Useful Tips

Screen Updating By setting Screen Updating to False, the user will not see all of the changes that the

code is doing to the workbook until it is finished runningApplication.ScreenUpdating = False

Use a lots of comments A single quote ‘ is used to comment lines of code

Hiding SheetsSheets(“DataDrop").Visible = False

Outputting to Specific SheetsSheets("Output”).Cells(17, 2) = “Territory Name”

Range(“Test_Range”).row or .column will return the row/column that the named range is located in

Use meaningful variable names. Use at least one capital letter in variable names If they are typed correctly, VBA will capitalize them, making it easy to spot typos


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Other Useful Tips

CTRL + Space Brings up an auto complete menu that includes user defined functions and

variables after typing only a few letters

Turning off “Auto Syntax” If a line of code is unrecognized in VBA, you will get a message box alerting

you• This becomes an annoyance if you want to move away from the line of code before

you finish typing it To turn off: Tools Options Uncheck “Auto Syntax Check”

Use white space to separate logic blocks

Make sure to lower the “Macro Security” level to medium in Excel otherwise you will not be able to enable the use of macros In Excel: Tools Macro Security Medium


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Agenda







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ActiveX Data Objects (ADO)

Open Database Connectivity (ODBC) and OLE DB is the underlying technology, application programming interface (API) that interfaces between our programs and the source of data, such as Access, SQL Server, Oracle, etc. Used in Windows C and C++

programming

ADO are ActiveX objects that provides easy access to the OLE DB and ODBC functionality. Used in Visual Basic and Java.

Microsoft Data Access Components (MDAC) ties it all together by packaging ADO with the necessary OLE DB providers


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ADO Object Model

The diagram below shows the objects.

Three objects you need know


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Relationship of ADO Objects

Connectionallows a

Commandmay return

Recordset


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Add ADO References in Excel

Microsoft ActiveX Data Objects 2.x Library The latest version is 2.8.


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ADO Objects

Connection object The Connection object sets up a link between your program and the data source. This

object contains all of the necessary configuration information and acts as a gateway for all of the other ADO objects.

Command object The Command object executes SQL strings, stored procedures, or action queries. Command objects may have an associated collection of Parameter objects that provide

additional information to the data source when executing the command.

Recordset object Recordset object creates and manages a collection of records. It contains navigational

methods to move to a particular record. Each Recordset object is composed of a number of Field objects that represent individual

columns in the Recordset. Each command execution results in a Recordset containing the results of the query.


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Connection Object

Create connection objectDim objConn As ADODB.ConnectionSet objConn = New ADODB.ConnectionObjConn.Open =”DSN=myDSN;UID=master;PWD=slave”

Close a connectionobjConn.CloseSET objConn=Nothing

Connection String - designates data source name and tells which provider is being used. ODBC data source name: DSN = myDSN. This is used when connecting to SQL Server. Text string

• Access: Provider=Microsoft.Jet.OLEDB.3.51;Persist Security Info=False;Data Source=C:\My Documents\CP3013\demodb.mdb

• SQL Server: Provider=SQLOLEDB.1;Integrated Security=SSPI;Persist Security Info=False;Data source=[SQL Server machine name];Initial Catalog=[database name];

• It may also include information on user name and password


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Create a DSN to SQL Server


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Connection Example

Dim cn As ADODB.Connection Set cn = New ADODB.Connection cn.ConnectionString = "DSN=Demodsn” 'or

'cn.ConnectionString = "Provider=Microsoft.Jet.OLEDB.4.0;Persist _ Security Info=False;Data Source=C:\My _Documents\CP3013\demodb.mdb"

cn.Open 'or 'cn.Open = "DSN=Demodsn“

'Code creating recordset accessing data source

cn.Close Set cn = Nothing


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Command Object

Two ways to create a Command object: Way 1:

Set objCmd = new ADODB.CommandSet objCmd.ActiveConnection = objConn

objCmd.CommandText=”qryPhoneMessagesFor” Way 2:

objCmd.ActiveConnection = “dsn=intranet” OrobjCmd.ActiveConnection = ”DRIVER={Microsoft Access

Driver(*.mdb)}; DBQ=c:\data\…..\XXX.mdb”

Both Command and Connection objects have a method named Execute. Syntax: .Execute (RecordsAffcted, Parameters, Options) Give it an SQL command (as a parameter) and it creates a Recordset object.

The Recordset object contains the result of the SQL query. Set result=objCmd.Execute("SELECT * FROM Password")

Resulting Recordset object


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Command Object (Cont.)

Command time out: time (secs) ADO waits for command to be returned before aborting Example: objComm.CommandTimeout = 0. 0 means infinity.

Command type specifies the type of command object to be or being used, types are adCmdText: Evaluates CommandText as a textual definition of a command or

stored procedure call. adCmdTable: Evaluates CommandText as table name whose columns are

all returned by internally generated SQL query. adCmdStoredProc: Evaluates CommandText as a stored procedure name. adCmdUnknown: Default. The type of command in the CommandText

property is not known


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Recordset Object

The recordset object has its own methods and properties to retrieve data First need to create new instance of object

Dim rs As ADODB.RecordsetSet rs = New ADODB.Recordset

Use properties to specify connection, record source and recordset type For Connection could put

rs.ActiveConnection = cn ‘cn is open connection orrs.ActiveConnection = “DSN=Demodsn” ‘Opens own connection to database

Use recordset’s ‘Open’ method to populate recordset with dataSet rs = New ADODB.Recordset

rs.ActiveConnection = cnrs.Source = SQLStatement

rs.Open

Or: Set rsobject = cnobject.Execute(SQL statement)


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Recordset Object Methods

A RecordSet object holds a collection of records (from the database) and has some methods: EOF() : boolean that indicates there are no more records. MoveNext(): moves to the next record MovePrevious(): move to previous record MoveFirst(): move to the first record GetRows(): Fetches a block of rows into an array. Very efficient when retrieving

a big data set into memory. Lots more…


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Looping Over All Records Returned

Without “MoveNext”, this code will run forever. Recordset object should be closed once you finishes it.


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Recordset Object (Cont.)

Adding DataRst.AddnewRst(“field1”) = value1Rst(“field2”) = value2………….Rst.Update (EX. Addcust1.html)

Updating dataRst(“field1”) = value1……rst.Update(EX. Update.asp)

Delete• rs.Delete

Batch updatesRst.UpdateBatch


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Recordset: Cursor

A cursor is what manages the set of records and the current location within the recordset, the latter being handled by the current record pointer. A good way to think about it is to imagine the cursor as a single row window

that can move up and down the recordset.

Cursor is very important as it determines what you can do with the recordset.

Cursor location: determine where the cursor lives. Certain data source, such as SQL Server, have a cursor service of their own,

whereas others, such as Access, don’t have a cursor service. ADO has its own cursor service. Use CursoLocation property:

• adUseServer – To let the data source manipulate the cursor• adUseClient – To let ADO maninuplate the cursor.

The default cursor is server-based.


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Recordset: Cursor Type

Determines how you can move through the recordset. It can only be specified upon opening a recordset

Specify it using CursorType property in recordset object or as the third parameter using .Open method Adopenforwardonly (Value 0) Default

• The data is alive but you can only move forward.• Cannot move backward or to specific record

Adopenkeyset (Value 1)• The data is alive and any record read will be the most recent data.

Adopendynamic (Value 2)• The data is alive and additions will be noticed.• Accurate recordcount.

Adopenstatic (Value 3)• The data is dead. It is like a snapshot of the data.• Accurate recordcount.


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Recordset: Lock Type

This affects data modification and concurrency Lock types:

AdLockReadOnly (Value 1) Default• Read-only recordset, no locking provided since data cannot be updated.

AdLockPessimistic (Value 2)• Attempts to lock record once editing starts.

AdLockOptimistic (Value 3)• Only locks the record when .Update method is used.

AdLockBatchOptimistic (Value 4)• Locks are issued when .UpdateBatch method is used

Performance considerations The fastest way to read data in is to use cursor type Adopenforwardonly and

lock type AdLockReadOnly.


86

ADO Example I


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ADO Example I (Cont.)

Query Results are now stored in the “arrDocID” and “arrDocName” arrays


88

ADO Example I (Cont.)


89

ADO Example II

This is a simplified version of a real life application: We have a list of dinner program participants with DocID stored in table T_Participants.

We have the prescription information of all physicians including those program participants, stored in table T_Prescription.

For each participant, we would like to find a control among all non-participants who has the closest 24th month prescription as the participant and whose scripts are no more and less than 20 of that of this participant.

At the end, we will save all participants with their identified controls into T_matched table with two columns: ParticipantID, and NonParticipantID.

We use this example to illustrate two things: How you can save results back to the database. You should always try to separate the logic into a few blocks and then put each block

into a function/procedure. This will make the whole code much easier to read and understand.

• In this example, we split the main logic into three pieces: read data, find controls, and save data.• Can you see how long the main() function will be if we put all code into it only?

We only show two functions here. For the complete code illustration, please refer to accompanied “VBA Example” excel file.


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ADO Example II – Main() function


91

ADO Example II – Matching_SaveData() function


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Agenda







93

Using the marketRx template

The standard marketRx template can be found at \\Filesrv\Marketing\marketingmaterial\Templates

• “Standard marketRx template - Read notes on Slide 1.ppt” There are notes on the first slide with an explanation on how to use the

template This should be used for all presentations created


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Using Charts and Graphs from Excel

Remember to always paste tables and graphs into PowerPoint as a Picture not as a direct paste

Ensures that data and formatting is not changed in the presentation

MAT 2001 MAT 2002 MAT 2003 MAT 2004

PAI Market € 4,794,808,856 € 5,445,855,733 € 5,833,228,293 € 6,525,998,076

Brand PAI Mkt € 216,808,363 € 213,596,344 € 225,108,099 € 249,900,617

Generic PAI Mkt € 4,578,000,493 € 5,232,259,389 € 5,608,120,194 € 6,276,097,459

Brand - % of Mkt 4.52% 3.92% 3.86% 3.83%

PAI Market Trends

€ 0

€ 1,000

€ 2,000

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MAT 2001 MAT 2002 MAT 2003 MAT 2004Year

Euro

s (M

illio

ns)

PAI Market

Brand PAI Mkt

Generic PAI Mkt


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Resizing and Cropping Images

By adding the picture toolbar (Right Click on the toolbar Click on “Picture”) you can select the “Crop” option This will allow you to crop off certain areas of the picture you paste

Resizing Pictures You can also right click on the picture and click on “Format Picture” The size tab will allow you to keep graphs and tables pasted from Excel the

same size throughout the presentation

€ 0

€ 1,000

€ 2,000

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€ 7,000

MAT 2001 MAT 2002 MAT 2003 MAT 2004Year

Euro

s (M

illio

ns)


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Aligning Object in PowerPoint

PowerPoint has several features that will help maintain the consistency of the placement of objects on slides throughout the presentation

Centering an object on the slide In the lower left hand corner of PowerPoint, there is a “Draw” menu

• Draw “Align or Distribute” “Relative to Slide”• Draw “Align or Distribute” “Align Center” : This will center the object horizontally on the

page• Draw “Align or Distribute” “Align Middle” : This will center the object vertically on the page

If there are multiple objects to align on the page, “Drawing Guides” are more useful Right click on the slide: Click “Grid and Guides” and Check “Display Drawing Guides on

Screen”• This place one centered vertical and one centered horizontal line on the slides• These lines can be duplicated (Click on the line, hold “Ctrl” and drag the line to a new position• By aligning these with objects in your presentation, it will help to maintain consistency

By Holding “Ctrl” and using the arrow keys, you will have greater control over the movement of the picture on the slide

VBA Training Presentation

Documents

button copyright

run button

macro step

commands macro copyright

button tool

linked macro

command button

size of button