versioned_docs/version-3.0/sql-manual/sql-functions/array-functions/array-union.md

---
{
    "title": "ARRAY_UNION",
    "language": "en"
}
---

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## array_union

array_union

### description

#### Syntax

`ARRAY<T> array_union(ARRAY<T> array1, ARRAY<T> array2)`

Returns an array of the elements in the union of array1 and array2, without duplicates. If the input parameter is null, null is returned.

### example

```
mysql> select k1,k2,k3,array_union(k2,k3) from array_type_table;
+------+-----------------+--------------+-------------------------+
| k1   | k2              | k3           | array_union(`k2`, `k3`) |
+------+-----------------+--------------+-------------------------+
|    1 | [1, 2, 3]       | [2, 4, 5]    | [1, 2, 3, 4, 5]         |
|    2 | [2, 3]          | [1, 5]       | [2, 3, 1, 5]            |
|    3 | [1, 1, 1]       | [2, 2, 2]    | [1, 2]                  |
+------+-----------------+--------------+-------------------------+

mysql> select k1,k2,k3,array_union(k2,k3) from array_type_table_nullable;
+------+-----------------+--------------+-------------------------+
| k1   | k2              | k3           | array_union(`k2`, `k3`) |
+------+-----------------+--------------+-------------------------+
|    1 | [1, NULL, 3]    | [1, 3, 5]    | [1, NULL, 3, 5]         |
|    2 | [NULL, NULL, 2] | [2, NULL, 4] | [NULL, 2, 4]            |
|    3 | NULL            | [1, 2, 3]    | NULL                    |
+------+-----------------+--------------+-------------------------+

mysql> select k1,k2,k3,array_union(k2,k3) from array_type_table_varchar;
+------+----------------------------+----------------------------------+---------------------------------------------------+
| k1   | k2                         | k3                               | array_union(`k2`, `k3`)                           |
+------+----------------------------+----------------------------------+---------------------------------------------------+
|    1 | ['hello', 'world', 'c++']  | ['I', 'am', 'c++']               | ['hello', 'world', 'c++', 'I', 'am']              |
|    2 | ['a1', 'equals', 'b1']     | ['a2', 'equals', 'b2']           | ['a1', 'equals', 'b1', 'a2', 'b2']                |
|    3 | ['hasnull', NULL, 'value'] | ['nohasnull', 'nonull', 'value'] | ['hasnull', NULL, 'value', 'nohasnull', 'nonull'] |
|    4 | ['hasnull', NULL, 'value'] | ['hasnull', NULL, 'value']       | ['hasnull', NULL, 'value']                        |
+------+----------------------------+----------------------------------+---------------------------------------------------+

mysql> select k1,k2,k3,array_union(k2,k3) from array_type_table_decimal;
+------+------------------+-------------------+----------------------------+
| k1   | k2               | k3                | array_union(`k2`, `k3`)    |
+------+------------------+-------------------+----------------------------+
|    1 | [1.1, 2.1, 3.44] | [2.1, 3.4, 5.4]   | [1.1, 2.1, 3.44, 3.4, 5.4] |
|    2 | [NULL, 2, 5]     | [NULL, NULL, 5.4] | [NULL, 2, 5, 5.4]          |
|    4 | [1, NULL, 2, 5]  | [1, 3.1, 5.4]     | [1, NULL, 2, 5, 3.1, 5.4]  |
+------+------------------+-------------------+----------------------------+

```

### keywords

ARRAY,UNION,ARRAY_UNION