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
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)