# FOR

The FOR statement creates a loop that iterates over the values of an array.

The `FOR` statement can be used to iterate over the values of an array, and to perform certain actions with those values.

> [!NOTE]
> A `FOR` loop currently cannot modify items outside its own scope, such as variables declared before the loop.

**SurrealQL Syntax**

```syntax title="SurrealQL Syntax"
FOR @item IN @iterable {
@block
};
```

## Example usage
The following query shows example usage of this statement.

```surql
-- Create a person for everyone in the array
FOR $name IN ['Tobie', 'Jaime'] {
	CREATE type::record('person', $name) CONTENT {
		name: $name
	};
};
```

The following query shows the `FOR` statement being used update a property on every user matching certain criteria.

```surql
-- Set can_vote to true for every person over 18 years old.
FOR $person IN (SELECT VALUE id FROM person WHERE age >= 18) {
	UPDATE $person SET can_vote = true;
};
```

## Ranges in FOR loops

A `FOR` loop can also be made out of a [range UUID](/docs/reference/query-language/language-primitives/data-types/ranges.md) of integers.

```surql
FOR $year IN 0..=2024 {
    CREATE historical_events SET
        for_year = $year,
        events = "To be added";
};
```

## Limitations of FOR loops

Parameters declared outside of a `FOR` loop can be used inside the loop.

```surql
LET $table1 = "person";
LET $table2 = "cat";

FOR $key in 0..4 {
    CREATE type::record($table1, $key);
	  CREATE type::record($table2, $key);
};
```

However, they currently cannot be modified inside a loop, making an operation like the following impossible.

```surql
LET $init = [];

FOR $num IN 1..=3 {
	$init += $num;
};
-- Error: 'assignment operators are only allowed in SET and DUPLICATE KEY UPDATE clauses'

RETURN $init;
```

In this case, the [`array::fold`](/docs/reference/query-language/functions/database-functions/array.md#arrayfold) and [`array::reduce`](/docs/reference/query-language/functions/database-functions/array.md#arrayreduce) functions can often be used to accomplish the intended behaviour.

```surql
(<array>1..=3).reduce(|$one, $two| $one + $two);
```

```surql title="Output"
6
```