SQL Server ISNULL() Function
The ISNULL() function in SQL Server provides a way to handle potential NULL values in your data. It allows you to replace NULL values with a specified value, making your data cleaner and easier to work with.
ISNULL(): Definition and Usage
NULL values can sometimes cause issues in your queries or applications. ISNULL() solves this by letting you substitute a NULL with a value you choose. If the expression isn't NULL, the function simply returns the expression's original value.
Syntax
Syntax
ISNULL(expression, value)
Parameter Values
| Parameter | Description |
|---|---|
expression |
The expression you are checking for NULL. This is required. |
value |
The value to return if the expression is NULL. This is required. |
Examples
Replacing a NULL Value
This example replaces a NULL with the string 'W3Schools.com'.
Syntax
SELECT ISNULL(NULL, 'W3Schools.com');
Output
W3Schools.com
Handling a Non-NULL Value
If the expression isn't NULL, the original value is returned.
Syntax
SELECT ISNULL('Hello', 'W3Schools.com');
Output
Hello
Replacing NULL with a Number
Replacing a NULL with a numeric value.
Syntax
SELECT ISNULL(NULL, 500);
Output
500