| --- |
| { |
| "title": "ARRAY_DISTINCT", |
| "language": "en" |
| } |
| --- |
| |
| ## array_distinct |
| |
| array_distinct |
| |
| ### description |
| |
| #### Syntax |
| |
| `ARRAY<T> array_distinct(ARRAY<T> arr)` |
| |
| Return the array which has been removed duplicate values. |
| Return NULL for NULL input. |
| |
| ### example |
| |
| ``` |
| mysql> select k1, k2, array_distinct(k2) from array_test; |
| +------+-----------------------------+---------------------------+ |
| | k1 | k2 | array_distinct(k2) | |
| +------+-----------------------------+---------------------------+ |
| | 1 | [1, 2, 3, 4, 5] | [1, 2, 3, 4, 5] | |
| | 2 | [6, 7, 8] | [6, 7, 8] | |
| | 3 | [] | [] | |
| | 4 | NULL | NULL | |
| | 5 | [1, 2, 3, 4, 5, 4, 3, 2, 1] | [1, 2, 3, 4, 5] | |
| | 6 | [1, 2, 3, NULL] | [1, 2, 3, NULL] | |
| | 7 | [1, 2, 3, NULL, NULL] | [1, 2, 3, NULL] | |
| +------+-----------------------------+---------------------------+ |
| |
| mysql> select k1, k2, array_distinct(k2) from array_test01; |
| +------+------------------------------------------+---------------------------+ |
| | k1 | k2 | array_distinct(`k2`) | |
| +------+------------------------------------------+---------------------------+ |
| | 1 | ['a', 'b', 'c', 'd', 'e'] | ['a', 'b', 'c', 'd', 'e'] | |
| | 2 | ['f', 'g', 'h'] | ['f', 'g', 'h'] | |
| | 3 | [''] | [''] | |
| | 3 | [NULL] | [NULL] | |
| | 5 | ['a', 'b', 'c', 'd', 'e', 'a', 'b', 'c'] | ['a', 'b', 'c', 'd', 'e'] | |
| | 6 | NULL | NULL | |
| | 7 | ['a', 'b', NULL] | ['a', 'b', NULL] | |
| | 8 | ['a', 'b', NULL, NULL] | ['a', 'b', NULL] | |
| +------+------------------------------------------+---------------------------+ |
| ``` |
| |
| ### keywords |
| |
| ARRAY, DISTINCT, ARRAY_DISTINCT |
| |
