ACC2000: Why a Calculated Control Appears Blank (209971)


The information in this article applies to:

  • Microsoft Access 2000
This article was previously published under Q209971
Novice: Requires knowledge of the user interface on single-user computers.

This article applies to a Microsoft Access database (.mdb) and to a Microsoft Access project (.adp).

SUMMARY

This article explains why a calculated control may appear blank.

MORE INFORMATION

When you have a calculation that contains a Null value, the result of the calculation is also Null. A Null value is not the same as zero; instead, it can be thought of as an unknown value. The result of adding an unknown value to a number is unknown.

When you have fields that contain Null values, you can create an expression that converts the Nulls to zero. You might do this if you want the records containing Null values to be included in an aggregate (totals) calculation, or if you want to prevent an expression from resulting in a Null value when a field that is referenced in the expression contains Nulls. To convert Null values to zero, use the Nz() function. For example:

Nz([Subtotal])+Nz([Freight])

REFERENCES

For more information about handling Null values, click Microsoft Access Help on the Help menu, type about working with blank fields in queries in the Office Assistant or the Answer Wizard, and then click Search to view the topics returned.
Modification Type:MajorLast Reviewed:6/28/2004
Keywords:kbinfo kbprogramming KB209971
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