# Rounding functions

Rounding functions choose a nearby representable number. The direction matters for negative values: floor moves toward negative infinity, while truncation moves toward zero.

## Syntax

```text
round(value [, digits])
ceil(value)
ceiling(value)
floor(value)
trunc(value)
```

## Behavior

| Function           | Rule                                                               |
| ------------------ | ------------------------------------------------------------------ |
| `round`            | Round to a number of decimal places; the default is zero.          |
| `ceil` / `ceiling` | Choose the least integer value greater than or equal to the input. |
| `floor`            | Choose the greatest integer value less than or equal to the input. |
| `trunc`            | Remove the fractional part toward zero.                            |

Ordinary floating-point round uses half-away-from-zero ties and clamps its requested decimal places to 0 through 30. Floating-point values remain approximate.

Decimal rounding preserves the declared scale. A carry into an additional integer digit can widen its precision to the next supported family. SQL NULL propagates.

## Examples

### Comparing directions

```sql
SELECT round(12.345, 2), ceil(1.2), floor(-1.2), trunc(-1.2)
FORMAT csv;
```

```text
12.35,2.0,-2.0,-1.0
```

### Exact decimal rounding

```sql
SELECT round(CAST('12.345' AS Decimal(18, 3)), 2)
FORMAT csv;
```

```text
12.350
```

See [Decimal](https://coordinatordb.com/docs/reference/data-types/decimal) and [floating-point types](https://coordinatordb.com/docs/reference/data-types/float) for precision and conversion rules.