The **`ISNULL()` function** returns `1` if the expression sent as a parameter is `NULL`; otherwise, it returns `0`. 

Figure 1 shows a visual representation of the `ISNULL()` function.

# Syntax
```sql
ISNULL(exp)
```
# Parameter
The `ISNULL()` function takes the expression as a parameter. 

# Return value
The `ISNULL()` function returns `1` if the expression sent as a parameter is `NULL`; otherwise, it returns `0`.

# Example





-- NULL expression
SELECT ISNULL(NULL);

-- not NULL expression
SELECT ISNULL('educative');

SELECT ISNULL(12345);

What is ISNULL() in SQL?

The ISNULL() function in SQL returns 1 if the expression is NULL, otherwise, it returns 0.