# `ARRAY_CAT`

**Applies to:** ✅ Data 360 SQL ✅ Tableau Hyper API

Concatenates two arrays into a single array.

## Syntax

```sql
array_cat(<array1>, <array2>)
```

## Arguments

### Required

- `<array1>`: The first array.
- `<array2>`: The second array to concatenate to the first.

## Returns

Returns an array that contains all elements from both input arrays in order.

## Considerations

- The resulting element type is non-nullable only if both input element types are non-nullable.
- Both arrays must have compatible element types, otherwise your SQL query will fail.

## Examples

### Concatenate Two Arrays

Combine two arrays.

```sql
SELECT array_cat(array[1, 2], array[3, 4]) AS result;
```

Returns `array[1, 2, 3, 4]`, combining both arrays.

### Concatenate with NULL Elements

Combine arrays where one contains NULL values.

```sql
SELECT array_cat(array[1, null], array[3, 4]) AS result;
```

Returns `array[1, null, 3, 4]`. The resulting element type is nullable when either input contains NULL.

## Related Documentation

- [Array Data Type](/docs/data/data-cloud-query-guide/references/dc-sql-reference/array.md)