# IS\$1NOT\$1NULL expression
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The IS\$1NOT\$1NULL conditional expression is used to check if a value is not null.

This expression is a synonym for IS NOT NULL.

## Syntax
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```
is_not_null(expr)
```

## Arguments
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*expr*  
An expression of any type.

## Returns
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The IS\$1NOT\$1NULL conditional expression returns a Boolean. If `expr1` is not NULL, returns `true`, otherwise returns `false`.

## Examples
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The following example checks if the value `1` is not null, and returns the boolean result `true` because 1 is a valid, non-null value.

```
SELECT is not null(1);
 true
```

The following example selects the `id` column from the `squirrels` table, but only for the rows where the age column is not `null`.

```
SELECT id FROM squirrels WHERE is_not_null(age)
```