How to set access verification rules that cannot be null

In order to solve the problem that Access validation rules cannot be null values, there are two methods: one is to use NULL values, and the other is to use the Nz() function to convert the field value to a non-null value. The former uses the IS NULL expression to check whether a field is NULL, and the latter uses the Nz() function to return an empty string.

How to solve the problem that Access validation rules cannot be empty

Problem:

Access validation rules cannot be set to a null value.

Solution:

There are two ways to solve this problem:

Method 1: Use NULL value

Use NULL value to indicate that the field can be empty.

• In the validation rule text box, enter the following expression:

<code>IS NULL</code>

Method 2: Use the Nz() function

## The #Nz() function returns a non-null value.

In the validation rule text box, enter the following expression:

<code>Nz([Field Name], "")</code>

Where: [Field Name] is the name of the field to be validated.

Detailed explanation:

• NULL value: IS NULL The expression checks whether the field is NULL. If NULL, the validation rule passes.
• Nz() function: Nz() Function converts a field value to a non-null value. If the field is empty, the Nz() function returns an empty string ("").

Both methods allow you to set null values ​​for Access validation rules. Which method to choose depends on the specific requirements of your data.

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