# IS

## Overview

Boolean comparison.

## USAGE

```expression IS TRUE|FALSE|UNKNOWN
```

Value Name

Description

`expression`

A value expression

## DETAILS

The `IS` operator returns a truth value for one of 3 boolean comparisons:

• `x IS TRUE` checks if the expression evaluates to `TRUE` (a non-zero value)

• `x IS FALSE` checks if the expression evaluates to `FALSE` (a zero value)

• `x IS UNKNOWN` checks if the expression has no known value (is `NULL`)

The return value is always `1` (true) or `0` (false). Evaluating a `NULL` value does not return `NULL` because this operator considers it to be `UNKNOWN` and never `TRUE` or `FALSE`.

See IS NOT for the negated version of these comparisons.

## EXAMPLES

```SELECT 1 IS TRUE, 1 IS FALSE, 1 IS UNKNOWN;
```
```+-----------+------------+--------------+
| 1 IS TRUE | 1 IS FALSE | 1 IS UNKNOWN |
+-----------+------------+--------------+
|         1 |          0 |            0 |
+-----------+------------+--------------+
```
```SELECT 0 IS TRUE, 0 IS FALSE, 0 IS UNKNOWN;
```
```+-----------+------------+--------------+
| 0 IS TRUE | 0 IS FALSE | 0 IS UNKNOWN |
+-----------+------------+--------------+
|         0 |          1 |            0 |
+-----------+------------+--------------+
```
```SELECT NULL IS TRUE, NULL IS FALSE, NULL IS UNKNOWN;
```
```+--------------+---------------+-----------------+
| NULL IS TRUE | NULL IS FALSE | NULL IS UNKNOWN |
+--------------+---------------+-----------------+
|            0 |             0 |               1 |
+--------------+---------------+-----------------+
```
```SELECT 42 = TRUE, 42 IS TRUE;
```
```+-----------+------------+
| 42 = TRUE | 42 IS TRUE |
+-----------+------------+
|         0 |          1 |
+-----------+------------+
```

## CHANGE HISTORY

Release Series

History

23.09

• Present starting in MariaDB Xpand 23.09.1.

6.1

• Present starting in MariaDB Xpand 6.1.0.

6.0

• Present starting in MariaDB Xpand 6.0.3.

5.3

• Present starting in MariaDB Xpand 5.3.13.

Release Series

History

6.0

• Present starting in MariaDB Xpand 6.0.3.

5.3

• Present starting in MariaDB Xpand 5.3.13.

Release Series

History

6.1

• Present starting in MariaDB Xpand 6.1.0.