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

# Comparisons

<h3 id="comparison\_operators">
  Comparison operators \\
</h3>

| Operator | Description                                 |
| -------- | ------------------------------------------- |
| `<`      | Less than                                   |
| `>`      | Greater than                                |
| `<=`     | Less than or equal to                       |
| `>=`     | Greater than or equal to                    |
| `=`      | Equal                                       |
| `<>`     | Not equal                                   |
| `!=`     | Not equal (non-standard but popular syntax) |

### Range operator: BETWEEN

The `BETWEEN` operator tests if a value is within a specified range. It
uses the syntax `value BETWEEN min AND max`:

```sql
    SELECT 3 BETWEEN 2 AND 6;
```

The statement shown above is equivalent to the following statement:

```sql
    SELECT 3 >= 2 AND 3 <= 6;
```

To test if a value does not fall within the specified range use
`NOT BETWEEN`:

```sql
    SELECT 3 NOT BETWEEN 2 AND 6;
```

The statement shown above is equivalent to the following statement:

```sql
    SELECT 3 < 2 OR 3 > 6;
```

A `NULL` in a `BETWEEN` or `NOT BETWEEN` statement is evaluated using
the standard `NULL` evaluation rules applied to the equivalent
expression above:

```sql
    SELECT NULL BETWEEN 2 AND 4; -- null

    SELECT 2 BETWEEN NULL AND 6; -- null

    SELECT 2 BETWEEN 3 AND NULL; -- false

    SELECT 8 BETWEEN NULL AND 6; -- false
```

The `BETWEEN` and `NOT BETWEEN` operators can also be used to evaluate
any orderable type. For example, a `VARCHAR`:

```sql
    SELECT 'Paul' BETWEEN 'John' AND 'Ringo'; -- true
```

Note that the value, min, and max parameters to `BETWEEN` and
`NOT BETWEEN` must be the same type. For example, Trino will produce an
error if you ask it if John is between 2.3 and 35.2.

### IS NULL and IS NOT NULL

The `IS NULL` and `IS NOT NULL` operators test whether a value is null
(undefined). Both operators work for all data types.

Using `NULL` with `IS NULL` evaluates to true:

```sql
    select NULL IS NULL; -- true
```

But any other constant does not:

```sql
    SELECT 3.0 IS NULL; -- false
```

<h3 id="is\_distinct\_operator">
  IS DISTINCT FROM and IS NOT DISTINCT FROM \\
</h3>

In SQL a `NULL` value signifies an unknown value, so any comparison
involving a `NULL` will produce `NULL`. The `IS DISTINCT FROM` and
`IS NOT DISTINCT FROM` operators treat `NULL` as a known value and both
operators guarantee either a true or false outcome even in the presence
of `NULL` input:

```sql
    SELECT NULL IS DISTINCT FROM NULL; -- false

    SELECT NULL IS NOT DISTINCT FROM NULL; -- true
```

In the example shown above, a `NULL` value is not considered distinct
from `NULL`. When you are comparing values which may include `NULL` use
these operators to guarantee either a `TRUE` or `FALSE` result.

The following truth table demonstrate the handling of `NULL` in
`IS DISTINCT FROM` and `IS NOT DISTINCT FROM`:

| a      | b      | a = b   | a \<> b | a DISTINCT b | a NOT DISTINCT b |
| ------ | ------ | ------- | ------- | ------------ | ---------------- |
| `1`    | `1`    | `TRUE`  | `FALSE` | `FALSE`      | > `TRUE`         |
| `1`    | `2`    | `FALSE` | `TRUE`  | `TRUE`       | > `FALSE`        |
| `1`    | `NULL` | `NULL`  | `NULL`  | `TRUE`       | > `FALSE`        |
| `NULL` | `NULL` | `NULL`  | `NULL`  | `FALSE`      | > `TRUE`         |

### GREATEST and LEAST

These functions are not in the SQL standard, but are a common extension.
Like most other functions in Trino, they return null if any argument is
null. Note that in some other databases, such as PostgreSQL, they only
return null if all arguments are null.

The following types are supported: `DOUBLE`, `BIGINT`, `VARCHAR`,
`TIMESTAMP`, `TIMESTAMP WITH TIME ZONE`, `DATE`

#### greatest ()

**`greatest(value1, value2, ..., valueN)`** →  \[same as input]

Returns the largest of the provided values.

#### least ()

**`least(value1, value2, ..., valueN)`** →  \[same as input]

Returns the smallest of the provided values.

<h3 id="quantified\_comparison\_predicates">
  Quantified comparison predicates: ALL, ANY and SOME \\
</h3>

The `ALL`, `ANY` and `SOME` quantifiers can be used together with
comparison operators in the following way:

```text
expression operator quantifier ( subquery )
```

For example:

```sql

    SELECT 'hello' = ANY (VALUES 'hello', 'world'); -- true

    SELECT 21 < ALL (VALUES 19, 20, 21); -- false

    SELECT 42 >= SOME (SELECT 41 UNION ALL SELECT 42 UNION ALL SELECT 43); -- true
```

Here are the meanings of some quantifier and comparison operator
combinations:

| Expression       | Meaning                                                                                              |
| ---------------- | ---------------------------------------------------------------------------------------------------- |
| `A = ALL (...)`  | Evaluates to `true` when `A` is equal to all values.                                                 |
| `A <> ALL (...)` | Evaluates to `true` when `A` doesn't match any value.                                                |
| `A < ALL (...)`  | Evaluates to `true` when `A` is smaller than the smallest value.                                     |
| `A = ANY (...)`  | Evaluates to `true` when `A` is equal to any of the values. This form is equivalent to `A IN (...)`. |
| `A <> ANY (...)` | Evaluates to `true` when `A` doesn't match one or more values.                                       |
| `A < ANY (...)`  | Evaluates to `true` when `A` is smaller than the biggest value.                                      |

`ANY` and `SOME` have the same meaning and can be used interchangeably.

### Pattern comparison: LIKE

The `LIKE` operator can be used to compare values with a pattern:

```text
    ... column [NOT] LIKE 'pattern' ESCAPE 'character';
```

Matching characters is case sensitive, and the pattern supports two
symbols for matching:

* `_` matches any single character
* `%` matches zero or more characters

Typically it is often used as a condition in `WHERE` statements. An
example is a query to find all continents starting with `E`, which
returns `Europe`:

```sql
    SELECT * FROM (VALUES 'America', 'Asia', 'Africa', 'Europe', 'Australia', 'Antarctica') AS t (continent)
    WHERE continent LIKE 'E%';
```

You can negate the result by adding `NOT`, and get all other continents,
all not starting with `E`:

```sql
    SELECT * FROM (VALUES 'America', 'Asia', 'Africa', 'Europe', 'Australia', 'Antarctica') AS t (continent)
    WHERE continent NOT LIKE 'E%';
```

If you only have one specific character to match, you can use the `_`
symbol for each character. The following query uses two underscores and
produces only `Asia` as result:

```sql
    SELECT * FROM (VALUES 'America', 'Asia', 'Africa', 'Europe', 'Australia', 'Antarctica') AS t (continent)
    WHERE continent LIKE 'A__A';
```

The wildcard characters `_` and `%` must be escaped to allow you to
match them as literals. This can be achieved by specifying the `ESCAPE`
character to use:

```sql
    SELECT 'South_America' LIKE 'South\_America' ESCAPE '\';
```

The above query returns `true` since the escaped underscore symbol
matches. If you need to match the used escape character as well, you can
escape it.

If you want to match for the chosen escape character, you simply escape
itself. For example, you can use `\\` to match for `''''`.