> ## Documentation Index
> Fetch the complete documentation index at: https://docs.regatta.dev/llms.txt
> Use this file to discover all available pages before exploring further.

# Comparison Functions and Operators

All the following operators return `BOOLEAN`.

The right arrow (⇒ ) indicates the result.

`datatype` refers to an operand of any supported compatible data type (see [Data Types](/sql/data-types)).

`boolean` refers to an operand of `BOOLEAN` data type.

| Operator                                               | Description and Comments                                     | Example                                                               |
| :----------------------------------------------------- | :----------------------------------------------------------- | :-------------------------------------------------------------------- |
| `datatype < datatype`                                  | Less than                                                    | `8 < 7`<br />⇒ false                                                  |
| `datatype > datatype`                                  | Greater than                                                 | `8 > 7`<br />⇒ true                                                   |
| `datatype <= datatype`                                 | Less than or equal to                                        | `8 <= 8`<br />⇒ true                                                  |
| `datatype >= datatype`                                 | Greater than or equal to                                     | `8 >= 8`<br />⇒ true                                                  |
| `datatype = datatype`                                  | Equal                                                        | `7 = 7`<br />⇒ true                                                   |
| `datatype <> datatype`                                 | Not equal                                                    | `7 <> 7`<br />⇒ false                                                 |
| `datatype != datatype`                                 | Not equal                                                    | `7 != 7`<br />⇒ false                                                 |
| `datatype BETWEEN datatype AND datatype`               | Between (inclusive) the range endpoints.<br />See notes.     | `2 BETWEEN 1 AND 3`<br />⇒ true<br />`2 BETWEEN 3 AND 1`<br />⇒ false |
| `datatype NOT BETWEEN datatype AND datatype`           | Not between (inclusive) the range endpoints.<br />See notes. | `2 NOT BETWEEN 1 AND 3`<br />⇒ false                                  |
| `datatype BETWEEN SYMMETRIC datatype AND datatype`     | Between, after sorting the two endpoint values               | `2 BETWEEN SYMMETRIC 3 AND 1`<br />⇒ true                             |
| `datatype NOT BETWEEN SYMMETRIC datatype AND datatype` | Not between, after sorting the two endpoint values           | `2 NOT BETWEEN SYMMETRIC 3 AND 1`<br />⇒ false                        |
| `datatype IS NULL`                                     | Check whether value is NULL.<br />See notes.                 | `5 IS NULL`<br />⇒ false                                              |
| `datatype IS NOT NULL`                                 | Check whether value is not NULL.<br />See notes.             | `5 IS NOT NULL`<br />⇒ true                                           |
| `boolean IS TRUE`                                      | Check whether boolean expression produces true               | `5 < 6 IS TRUE`<br />⇒ false                                          |
| `boolean IS NOT TRUE`                                  | Check whether boolean expression produces false or unknown   | `NULL::boolean IS NOT TRUE`<br />⇒ true                               |
| `boolean IS FALSE`                                     | Check whether boolean expression produces false              | `NULL::boolean IS FALSE`<br />⇒ false                                 |
| `boolean IS NOT FALSE`                                 | Check whether boolean expression produces true or unknown    | `NULL::boolean IS NOT FALSE`<br />⇒ true                              |
| `boolean IS UNKNOWN`                                   | Check whether boolean expression produces unknown            | `NULL::boolean IS UNKNOWN`<br />⇒ true                                |
| `boolean IS NOT UNKNOWN`                               | Check whether boolean expression produces true or false      | `NULL::boolean IS NOT UNKNOWN`<br />⇒ false                           |

#### Comparison Functions and Operators Notes

1. `BETWEEN` operator: it is expected that the first value is lower than the second one. If the first value is
   greater than the second one the result is an empty result set.

   To avoid the need to consider which of the two values is greater than the other, use the keyword `SYMMETRIC`.

   For example:

```sql theme={null}
SELECT o_date FROM orders WHERE (o_order_id BETWEEN SYMMETRIC 10 AND 1);
```

2. `NULL` is not “equal to” `NULL`, therefore, avoid using the expression `= NULL` and use `IS [ NOT ] NULL` instead.