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> Fetch the complete documentation index at: https://docs.firebolt.io/llms.txt
> Use this file to discover all available pages before exploring further.

> Reference material for IFNULL function

# IFNULL

Compares two expressions. Returns `<expression1>` if it’s non-NULL, otherwise returns `<expression2>`.

## Syntax

```sql theme={"theme":{"light":"css-variables","dark":"css-variables"}}
IFNULL(<expression1>, <expression2>)
```

## Parameters

| Parameter                        | Description                                                        | Supported input types |
| :------------------------------- | :----------------------------------------------------------------- | :-------------------- |
| `<expression1>`, `<expression2>` | Expressions that evaluate to any data type that Firebolt supports. | Any                   |

## Return Types

Same as input type

## Remarks

Use `ZEROIFNULL(<expression>)` as a synonym shorthand for `IFNULL(<expression>, 0)`.
`IFNULL(a, b)` has the same behaviour as `COALESCE(a, b)`.

## Examples

The following example shows the core behavior: `IFNULL` returns the original value when it is non-`NULL`, and returns the replacement when it is `NULL`:

<div className="query-window">
  ```
  SELECT val, IFNULL(val, 0) AS val_or_zero
  FROM UNNEST(ARRAY[1, NULL, 3, NULL, 5]) AS t(val)
  ORDER BY val NULLS LAST;
  ```

  | val <span>int null</span> | val\_or\_zero <span>int</span> |
  | :------------------------ | :----------------------------- |
  | 1                         | 1                              |
  | 3                         | 3                              |
  | 5                         | 5                              |
  | NULL                      | 0                              |
  | NULL                      | 0                              |

  <p><span>Rows: 5</span><span>Execution time: 4.15ms</span></p>
</div>

The following example uses `IFNULL` to replace the `nextlevel` value with `0` for the final level in the `levels` table, which has no next level (`NULL`):

<div className="query-window">
  ```
  SELECT level, name, nextlevel, IFNULL(nextlevel, 0) AS next_level_or_zero
  FROM levels
  ORDER BY level;
  ```

  | level <span>int null</span> | name <span>text null</span> | nextlevel <span>int null</span> | next\_level\_or\_zero <span>int</span> |
  | :-------------------------- | :-------------------------- | :------------------------------ | :------------------------------------- |
  | 1                           | Thunderbolt Circuit         | 2                               | 2                                      |
  | 2                           | Velocity Vale               | 3                               | 3                                      |
  | 3                           | Raceway Ridge               | 4                               | 4                                      |
  | 4                           | Nitro Narrows               | 5                               | 5                                      |
  | 5                           | Thunder Road                | 6                               | 6                                      |
  | 6                           | Burnout Boulevard           | 7                               | 7                                      |
  | 7                           | Speed Street                | 8                               | 8                                      |
  | 8                           | Racing Ravine               | 9                               | 9                                      |
  | 9                           | Drift District              | 10                              | 10                                     |
  | 10                          | Acceleration Alley          | NULL                            | 0                                      |

  <p><span>Rows: 10</span><span>Execution time: 6.00ms</span></p>
</div>