> For the complete documentation index, see [llms.txt](https://mariadb.com/docs/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://mariadb.com/docs/server/reference/sql-structure/operators/comparison-operators/is.md).

# IS

## Syntax

```bnf
IS boolean_value
```

## Description

Tests a value against a boolean value, where `boolean_value` can be `TRUE`, `FALSE`, or `UNKNOWN`.

There is an important difference between using `IS TRUE` or comparing a value with `TRUE` using `=`. When using `=`, only `1` equals to `TRUE`. But when using `IS TRUE`, all values which are logically true (like a number > 1) return `TRUE`.

## Examples

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

Difference between `=` and `IS TRUE`:

```sql
SELECT 2 = TRUE, 2 IS TRUE;
+----------+-----------+
| 2 = TRUE | 2 IS TRUE |
+----------+-----------+
|        0 |         1 |
+----------+-----------+
```

## See Also

* [Boolean Literals](/docs/server/reference/sql-structure/sql-language-structure/sql-language-structure-boolean-literals.md)
* [BOOLEAN Data Type](/docs/server/reference/data-types/numeric-data-types/boolean.md)
* [Operator Precedence](/docs/server/reference/sql-structure/operators/operator-precedence.md)

<sub>*This page is licensed: GPLv2, originally from*</sub> [<sub>*fill\_help\_tables.sql*</sub>](https://github.com/MariaDB/server/blob/main/scripts/fill_help_tables.sql)

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