Tài liệu Access 2007 VBA Programming docx

Access™ 2007 VBA

Programming

FOR

DUMmIES‰

01_046531 ffirs.qxp 1/16/07 9:07 PM Page i

01_046531 ffirs.qxp 1/16/07 9:07 PM Page ii

by Joseph C. Stockman and Alan Simpson

Access™ 2007 VBA

Programming

FOR

DUMmIES‰

01_046531 ffirs.qxp 1/16/07 9:07 PM Page iii

Access™ 2007 VBA Programming For Dummies®

Published by

Wiley Publishing, Inc.

111 River Street

Hoboken, NJ 07030-5774

www.wiley.com

Copyright © 2007 by Wiley Publishing, Inc., Indianapolis, Indiana

Published by Wiley Publishing, Inc., Indianapolis, Indiana

Published simultaneously in Canada

No part of this publication may be reproduced, stored in a retrieval system or transmitted in any form or

by any means, electronic, mechanical, photocopying, recording, scanning or otherwise, except as permit￾ted under Sections 107 or 108 of the 1976 United States Copyright Act, without either the prior written

permission of the Publisher, or authorization through payment of the appropriate per-copy fee to the

Copyright Clearance Center, 222 Rosewood Drive, Danvers, MA 01923, (978) 750-8400, fax (978) 646-8600.

Requests to the Publisher for permission should be addressed to the Legal Department, Wiley Publishing,

Inc., 10475 Crosspoint Blvd., Indianapolis, IN 46256, (317) 572-3447, fax (317) 572-4355, or online at

http://www.wiley.com/go/permissions.

Trademarks: Wiley, the Wiley Publishing logo, For Dummies, the Dummies Man logo, A Reference for the

Rest of Us!, The Dummies Way, Dummies Daily, The Fun and Easy Way, Dummies.com, and related trade

dress are trademarks or registered trademarks of John Wiley & Sons, Inc. and/or its affiliates in the United

States and other countries, and may not be used without written permission. Microsoft and Access are

trademarks or registered trademarks of Microsoft Corporation in the United States and/or other coun￾tries. All other trademarks are the property of their respective owners. Wiley Publishing, Inc., is not asso￾ciated with any product or vendor mentioned in this book.

LIMIT OF LIABILITY/DISCLAIMER OF WARRANTY: THE PUBLISHER AND THE AUTHOR MAKE NO REP￾RESENTATIONS OR WARRANTIES WITH RESPECT TO THE ACCURACY OR COMPLETENESS OF THE

CONTENTS OF THIS WORK AND SPECIFICALLY DISCLAIM ALL WARRANTIES, INCLUDING WITHOUT

LIMITATION WARRANTIES OF FITNESS FOR A PARTICULAR PURPOSE. NO WARRANTY MAY BE CRE￾ATED OR EXTENDED BY SALES OR PROMOTIONAL MATERIALS. THE ADVICE AND STRATEGIES CON￾TAINED HEREIN MAY NOT BE SUITABLE FOR EVERY SITUATION. THIS WORK IS SOLD WITH THE

UNDERSTANDING THAT THE PUBLISHER IS NOT ENGAGED IN RENDERING LEGAL, ACCOUNTING, OR

OTHER PROFESSIONAL SERVICES. IF PROFESSIONAL ASSISTANCE IS REQUIRED, THE SERVICES OF A

COMPETENT PROFESSIONAL PERSON SHOULD BE SOUGHT. NEITHER THE PUBLISHER NOR THE

AUTHOR SHALL BE LIABLE FOR DAMAGES ARISING HEREFROM. THE FACT THAT AN ORGANIZATION

OR WEBSITE IS REFERRED TO IN THIS WORK AS A CITATION AND/OR A POTENTIAL SOURCE OF FUR￾THER INFORMATION DOES NOT MEAN THAT THE AUTHOR OR THE PUBLISHER ENDORSES THE

INFORMATION THE ORGANIZATION OR WEBSITE MAY PROVIDE OR RECOMMENDATIONS IT MAY

MAKE. FURTHER, READERS SHOULD BE AWARE THAT INTERNET WEBSITES LISTED IN THIS WORK

MAY HAVE CHANGED OR DISAPPEARED BETWEEN WHEN THIS WORK WAS WRITTEN AND WHEN IT

IS READ. FULFILLMENT OF EACH COUPON OFFER IS THE SOLE RESPONSIBILITY OF THE OFFEROR.

For general information on our other products and services, please contact our Customer Care

Department within the U.S. at 800-762-2974, outside the U.S. at 317-572-3993, or fax 317-572-4002.

For technical support, please visit www.wiley.com/techsupport.

Wiley also publishes its books in a variety of electronic formats. Some content that appears in print may

not be available in electronic books.

Library of Congress Control Number: 2006939596

ISBN: 978-0-470-04653-1

Manufactured in the United States of America

01_046531 ffirs.qxp 1/16/07 9:07 PM Page iv

01_046531 ffirs.qxp 1/16/07 9:07 PM Page vi

Dedication

Joe Stockman: To my mom and all my friends and family who supported me —

and left me alone — during this project.

Alan Simpson: To Susan, Ashley, and Alec, as always.

Authors’ Acknowledgments

Even though only two authors’ names appear on the cover, every book is a

team project. These authors would like to thank the many people who con￾tributed to this book. To Carole McClendon and everyone at Waterside

Productions, thank you for finding this project and making it happen. Also,

many thanks to Kyle Looper and Jean Rogers at Wiley for taking a chance on

a new author to help with the rewrite. And also, thanks to Microsoft for

making Access a wonderful development environment.

01_046531 ffirs.qxp 1/16/07 9:07 PM Page vii

About the Author

Joe Stockman is an independent consultant, software designer, and author

who has been using Microsoft Access since its initial release. He’s also devel￾oped courseware and taught classes in Access and VBA. Joe developed his

first application in Access, and then migrated into Visual Basic and VB.NET,

where he specializes in creating applications for the Windows Mobile plat￾form. He worked for several software companies before forming his consult￾ing business in 2002, where he deals with all types of clients including

healthcare, financial, government, manufacturing, and small business. His

ability to turn his customers’ wishes into working applications keeps them

satisfied. Joe’s also writing the fundamentals column for the Advisor Guide to

Microsoft Access magazine.

Alan Simpson is the author of over 100 computer books on databases,

Windows, Web site design and development, programming, and networking.

His books are published throughout the world in over a dozen languages

and have millions of copies. Alan has also taught introductory and advanced

computer programming courses at San Diego State University and the UCSD

Extension. He has served as a consultant on high-technology, education￾oriented projects for the United States Navy and Air Force. Despite that,

Alan has no fancy job title because he has never had a real job.

01_046531 ffirs.qxp 1/16/07 9:07 PM Page v

Publisher’s Acknowledgments

We’re proud of this book; please send us your comments through our online registration form

located at www.dummies.com/register/.

Some of the people who helped bring this book to market include the following:

Acquisitions, Editorial, and Media

Development

Associate Project Editor: Jean Rogers

(Previous Edition: Christopher Morris)

Acquisitions Editor: Kyle Looper

Copy Editor: Becky Whitney

Technical Editor: Russ Mullen

Editorial Manager: Kevin Kirschner

Media Development Specialists: Angela Denny,

Kate Jenkins, Steven Kudirka, Kit Malone

Media Development Coordinator:

Laura Atkinson

Media Project Supervisor: Laura Moss

Media Development Manager: Laura VanWinkle

Media Development Associate Producer:

Richard Graves

Editorial Assistant: Amanda Foxworth

Sr. Editorial Assistant: Cherie Case

Cartoons: Rich Tennant

(www.the5thwave.com)

Composition Services

Project Coordinator: Jennifer Theriot

Layout and Graphics: Carl Byers,

Stephanie D. Jumper, Barbara Moore,

Barry Offringa, Alicia B. South

Proofreaders: Techbooks, Brian H. Walls

Indexer: Techbooks

Anniversary Logo Design: Richard Pacifico

Publishing and Editorial for Technology Dummies

Richard Swadley, Vice President and Executive Group Publisher

Andy Cummings, Vice President and Publisher

Mary Bednarek, Executive Acquisitions Director

Mary C. Corder, Editorial Director

Publishing for Consumer Dummies

Diane Graves Steele, Vice President and Publisher

Joyce Pepple, Acquisitions Director

Composition Services

Gerry Fahey, Vice President of Production Services

Debbie Stailey, Director of Composition Services

01_046531 ffirs.qxp 1/16/07 9:07 PM Page viii

Contents at a Glance

Introduction .................................................................1

Part I: Introducing VBA Programming............................7

Chapter 1: Where VBA Fits In............................................................................................9

Chapter 2: Your VBA Toolkit ...........................................................................................21

Chapter 3: Jumpstart: Creating a Simple VBA Program ..............................................35

Part II: VBA Tools and Techniques ...............................49

Chapter 4: Understanding Your VBA Building Blocks .................................................51

Chapter 5: Controlling Access through VBA.................................................................71

Chapter 6: Programming Access Forms ........................................................................87

Part III: VBA, Recordsets, and SQL............................115

Chapter 7: The Scoop on SQL and Recordsets...........................................................117

Chapter 8: Putting Recordsets to Work .......................................................................147

Part IV: Applying VBA in the Real World ...................173

Chapter 9: Creating Your Own Dialog Boxes...............................................................175

Chapter 10: Customizing Combo Boxes and List Boxes............................................201

Chapter 11: Creating Your Own Functions..................................................................239

Chapter 12: Testing and Debugging Your Code ..........................................................265

Part V: Reaching Out with VBA .................................293

Chapter 13: Using VBA with Multiple Databases........................................................295

Chapter 14: Integrating with Other Office Applications............................................315

Part VI: The Part of Tens ...........................................349

Chapter 15: Ten Commandments of Writing VBA ......................................................351

Chapter 16: Top Ten Nerdy VBA Tricks.......................................................................357

Index .......................................................................367

02_046531 ftoc.qxp 1/16/07 9:07 PM Page ix

02_046531 ftoc.qxp 1/16/07 9:07 PM Page x

Table of Contents

Introduction..................................................................1

About This Book...............................................................................................1

Conventions Used in This Book .....................................................................2

What You’re Not to Read.................................................................................2

Foolish Assumptions .......................................................................................3

How This Book Is Organized...........................................................................3

Part I: Introducing VBA Programming .................................................3

Part II: VBA Tools and Techniques.......................................................3

Part III: VBA, Recordsets, and SQL.......................................................4

Part IV: Applying VBA in the Real World .............................................4

Part V: Reaching Out with VBA.............................................................4

Part VI: The Part of Tens .......................................................................4

Icons Used in This Book..................................................................................4

Web Site for This Book ....................................................................................5

Where to Go from Here....................................................................................5

Part I: Introducing VBA Programming.............................7

Chapter 1: Where VBA Fits In . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9

Taking a Look at Access ................................................................................10

Understanding VBA........................................................................................11

Seeing Where VBA Lurks...............................................................................12

Finding standard modules...................................................................13

Finding class modules .........................................................................13

From VBA to Access.............................................................................15

Finding Out How VBA Works ........................................................................17

Discovering VBA procedures..............................................................17

Recognizing VBA procedures..............................................................18

Chapter 2: Your VBA Toolkit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .21

Using the Visual Basic Editor........................................................................21

Using Project Explorer.........................................................................23

Using the Properties window..............................................................24

Using the Immediate window..............................................................26

Using the Code window .......................................................................27

Referring to Objects from VBA.....................................................................29

Setting References to Object Libraries........................................................30

Using the Object Browser .............................................................................30

Searching the Object Library .......................................................................33

02_046531 ftoc.qxp 1/16/07 9:07 PM Page xi

xii Access 2007 VBA Programming For Dummies

Chapter 3: Jumpstart: Creating a Simple VBA Program . . . . . . . . . . . .35

Creating a Standard Module .........................................................................35

Creating a Procedure .....................................................................................36

Understanding Syntax ...................................................................................38

Getting keyword help...........................................................................40

Help with arguments............................................................................43

About named arguments .....................................................................45

Using Existing Code .......................................................................................46

Copy and paste code from the Web ...................................................46

Importing modules...............................................................................47

Modifying existing code.......................................................................48

Part II: VBA Tools and Techniques ................................49

Chapter 4: Understanding Your VBA Building Blocks . . . . . . . . . . . . .51

Commenting Your Code ................................................................................52

Understanding VBA Data Types...................................................................53

Passing Data to Procedures ..........................................................................54

Storing data in variables and constants............................................57

Storing data in arrays...........................................................................58

Module-level versus procedure-level.................................................60

Naming conventions for variables .....................................................61

Repeating Chunks of Code with Loops........................................................62

Using Do...Loop to create a loop ........................................................62

Using While...Wend to create a loop ..................................................64

Using For...Next to create a loop.........................................................64

Making Decisions in VBA Code.....................................................................66

Using If...End If statements..................................................................67

Using a Select Case block ....................................................................68

Chapter 5: Controlling Access through VBA . . . . . . . . . . . . . . . . . . . . . .71

Understanding Object Models......................................................................72

Distinguishing between objects and collections..............................72

Understanding properties and methods ...........................................75

Identifying the icons for objects, properties, and methods ...........77

Manipulating Properties and Methods........................................................79

Getting the value of a property...........................................................79

Changing the value of a property.......................................................81

Using an object’s methods ..................................................................82

Seeking help with properties and methods ......................................84

Chapter 6: Programming Access Forms . . . . . . . . . . . . . . . . . . . . . . . . .87

Working with Class Procedures....................................................................87

Enabling or Disabling Form Controls...........................................................90

Using VBA to position the cursor.......................................................91

Choosing an object and event for the code ......................................92

02_046531 ftoc.qxp 1/16/07 9:07 PM Page xii

Showing and hiding controls ..............................................................95

Making controls read-only...................................................................96

Responding to Form Events..........................................................................96

Changing the Appearance of Objects ..........................................................99

Changing colors....................................................................................99

Controlling boldface, italics, and such ............................................103

Changing special effects ....................................................................104

Using the With...End With statements .............................................104

Filling form controls with data .........................................................105

Opening and Closing Forms........................................................................107

Closing a form.....................................................................................109

Adding a related record to another table........................................109

More DoCmd methods for forms......................................................112

Part III: VBA, Recordsets, and SQL.............................115

Chapter 7: The Scoop on SQL and Recordsets . . . . . . . . . . . . . . . . . . .117

What the Heck Is SQL?.................................................................................117

Writing SQL without knowing SQL ...................................................120

Select queries versus action queries ...............................................121

Getting SQL into VBA .........................................................................123

Hiding warning messages..................................................................124

Storing SQL statements in variables................................................125

Creating Tables from VBA ...........................................................................128

Creating new tables from existing tables ........................................128

Creating a new, empty table from VBA ............................................129

Closing and deleting tables through VBA .......................................130

Adding Records to a Table..........................................................................131

Appending a single record with SQL................................................132

Query to append one record ............................................................133

Changing and Deleting Table Records.......................................................134

Performing an Action Query on One Record............................................136

Working with Select Queries and Recordsets...........................................137

Defining a connection ........................................................................140

Defining the recordset and data source ..........................................141

Filling the recordset with data..........................................................142

Managing recordsets..........................................................................143

Referring to fields in a recordset......................................................145

Closing recordsets and collections..................................................146

Chapter 8: Putting Recordsets to Work . . . . . . . . . . . . . . . . . . . . . . . . .147

Looping through Collections ......................................................................147

Using For Each loops .........................................................................149

Using shorter names for objects ......................................................152

xiii Table of Contents

02_046531 ftoc.qxp 1/16/07 9:07 PM Page xiii

xiv Access 2007 VBA Programming For Dummies

Tips on Reading and Modifying Code........................................................154

Square brackets represent names....................................................154

Other ways to refer to objects..........................................................155

The continuation character ..............................................................157

Skipping Over Used Mailing Labels ...........................................................159

Looking at How SkipLabels Works .............................................................162

Passing data to SkipLabels................................................................164

Declaring variables.............................................................................165

Copying the label report....................................................................165

Getting a report’s recordsource .......................................................165

Creating the recordset .......................................................................166

Creating LabelsTempTable from MyRecordSet ..............................166

Calling a Procedure from an Event ............................................................171

Part IV: Applying VBA in the Real World ....................173

Chapter 9: Creating Your Own Dialog Boxes . . . . . . . . . . . . . . . . . . . .175

Displaying and Responding to Messages..................................................176

Asking a question ...............................................................................176

Designing a message box...................................................................177

Responding to a MsgBox button click .............................................180

Converting Forms to Dialog Boxes ............................................................182

Storing dialog box settings................................................................183

Setting form properties .....................................................................184

Adding controls to the dialog box....................................................187

Creating Custom Combo Boxes..................................................................189

Creating a Spin Box Control........................................................................195

Detecting a Right-Click ................................................................................198

Chapter 10: Customizing Combo Boxes and List Boxes . . . . . . . . . . .201

Programming Combo and List Boxes ........................................................202

Listing field names .............................................................................204

Listing text options ............................................................................207

Listing Table/Query field values.......................................................212

Linking Lists..................................................................................................216

Running code when a form opens....................................................218

Running code when the user makes a choice.................................219

Linking Lists across Forms .........................................................................222

Updating a combo box or a list box.................................................223

Opening a form to enter a new record.............................................225

Seeing whether a form is open .........................................................226

Getting forms in sync.........................................................................227

More Combo Box Tricks..............................................................................228

Using hidden values in combo and list boxes ................................228

Giving users a quick find ...................................................................232

Avoiding retyping common entries..................................................235

02_046531 ftoc.qxp 1/16/07 9:07 PM Page xiv