Microsoft KB Archive Search

Notice: This website is an unofficial Microsoft Knowledge Base (hereinafter KB) archive and is intended to provide a reliable access to deleted content from Microsoft KB. All KB articles are owned by Microsoft Corporation. Read full disclaimer for more details.

  1. Home
  2. ACC2000: Using the AllowZeroLength and Required Properties

ACC2000: Using the AllowZeroLength and Required Properties

View products that this article applies to.

This article was previously published under Q209098
Novice: Requires knowledge of the user interface on single-user computers.

This article applies only to a Microsoft Access database (.mdb).

↑ Back to the top

Summary

The AllowZeroLength property determines whether a zero-length string ("") is a valid entry. The Required property determines whether a Null value is a valid value. Although these two properties work together, the AllowZeroLength property overrides the Required property.

↑ Back to the top

More information

The AllowZeroLength property determines whether a zero-length string ("") is a valid entry, and is available only for Text and Memo fields. Microsoft Access supports both the Null value and zero-length strings in Text and Memo fields.

The Required property determines whether a Null value is a valid value. Although the AllowZeroLength and Required properties work together, the AllowZeroLength property overrides the Required property. For example, if AllowZeroLength is set to Yes, a zero-length string is a valid value for the field regardless of the Required property setting. To enter a zero-length string in a field, type two double quotation marks ("").

You can use the AllowZeroLength and Required property settings to differentiate between information that does not exist and information that may exist. For example, you may have employees in your database who do not have a home phone. If AllowZeroLength is set to Yes, Required is set to No, and DefaultValue is left blank for the HomePhone field, you can type two double quotation marks to indicate that an employee does not have a home phone. If you leave the field blank (do not type text or delete any existing text), it indicates that the employee may have a home phone but you do not know what it is.

The following table shows the results you can expect when you combine the AllowZeroLength and Required property settings: 

AllowZeroLength    Required      User's action        Value displayed
 ---------------------------------------------------------------------

      No              No         Presses ENTER            <Null>
                                 Presses SPACEBAR         <Null>
                                 Types ""              (not allowed)



      Yes             No         Presses ENTER            <Null>
                                 Presses SPACEBAR         <Null>
                                 Types ""                   "" 



      No              Yes        Presses ENTER         (not allowed)
                                 Presses SPACEBAR      (not allowed)
                                 Types ""              (not allowed)



      Yes             Yes        Presses ENTER         (not allowed)
                                 Presses SPACEBAR           ""
                                 Types ""                   ""

↑ Back to the top

References

For more information about the AllowZeroLength property, click Microsoft Access Help on the Help menu, type allowzerolength property in the Office Assistant or the Answer Wizard, and then click Search to view the topics returned.

For more information about the Required property, click Microsoft Access Help on the Help menu, type required property in the Office Assistant or the Answer Wizard, and then click Search to view the topics returned.

↑ Back to the top

Keywords: KB209098, kbinfo, kbhowto

↑ Back to the top

Article Info
Article ID : 209098
Revision : 3
Created on : 7/15/2004
Published on : 7/15/2004
Exists online : False
Views : 262