Part 1 of "Keeping Your Information Accurate in Access 2003 and Access 2002": Introduction

The information covered in this article is provided by the Microsoft Press. For more information, visit the following Microsoft Web site: This article is part 1 of a series of eight articles that explain how to keep your information in Access accurate. To view the other articles in this series, see the "Additional resources" section later in this article.

This information is an excerpt from chapter 6: "Keeping Your Information Accurate" of the book Microsoft Access Version 2002 Step by Step. For more information about this book, see the "References" section.

Depending on how much information you have and how organized you are, you might compare a database to an old shoebox or a file cabinet, into which you toss items such as photographs, bills, receipts, and a variety of other paperwork for later retrieval. However, neither a shoebox nor a file cabinet restricts what you can place in it (other than how much you can place in it) or imposes any order on its content. It is up to you to decide what you store there and to organize it properly so that you can find it when you next need it. And neither a shoebox nor a file cabinet helps you with the task of updating your information when it changes or becomes obsolete.

When you create a database with Microsoft Access, you can set properties that restrict what can be entered in it, thereby keeping the database organized and useful. For example, The Garden Company wouldn't want its employees to enter text into fields that should contain numbers, such as price fields. Similarly, they wouldn't want to encourage employees to enter a long text description of something when a simple "yes" or "no" answer would work best. The field properties that control input are Required, Allow Zero Length, Field Size, Input Mask, and Validation Rule. The Required and Allow Zero Length properties are fairly obvious. If the Required property is set to Yes, the field can't be left blank. However, if Allow Zero Length is set to Yes, you can enter an empty string (two quotation marks with nothing in between), which looks like an empty field.

TIP: Each property has many options. For more information about how to use properties, search for field property in Access online Help.

To ensure the ongoing accuracy of a database, you can create and run action queries that quickly update information or delete selected records from a table. For example, The Garden Company might decide to increase the price of all products in one category by some percentage, or to remove one entire product line. This type of updating is easy to do with an action query. Not only does using a query save time, but it also avoids human input errors.

The exercises in this series of articles demonstrate how to use the data type and some of the field properties to restrict the data that can be entered in a table or form. It is difficult to experiment with field properties in a table that is already filled with information, because changing a field's data type or properties can destroy or alter the data.

Additional resources

For additional information, click the following article numbers to view the articles in the Microsoft Knowledge Base:

The information in this article is an excerpt from the Microsoft Access Version 2002 Step by Step book, published by Microsoft Press. To learn more about the Microsoft Access Version 2002 Step by Step book, and to see a sample chapter from this book, visit the following Microsoft Web site: For more information about this publication and about other Microsoft Press titles, visit the following Microsoft Web site: