MS Access IsNull() Function

The IsNull() function in MS Access checks whether an expression evaluates to NULL (meaning it doesn't have a value). It's a crucial function for handling missing data and preventing errors caused by NULL values.

IsNull(): Definition and Usage

IsNull() is frequently used in queries and VBA (Visual Basic for Applications) code to test for the absence of data. It returns a Boolean result: True (-1) if the expression is NULL, and False (0) otherwise. This allows you to handle NULL values appropriately in your applications.

Syntax


IsNull(expression)

Parameter Values

Parameter	Description
`expression`	The value or expression you want to check for `NULL`. This is required.

Examples

Testing for a NULL Value

This example explicitly checks if NULL is NULL.

Syntax


SELECT IsNull(null);

Output


True (-1)

Testing a Non-NULL String

This checks if a string value is NULL (it's not).

Syntax


SELECT IsNull("Hello");

Output


False (0)

Testing a Non-NULL Number

This example checks if the number 0 is NULL (it's not).

Syntax


SELECT IsNull(0);

Output


False (0)