array_distinct
description
Syntax
ARRAY<T> array_distinct(ARRAY<T> arr)返回去除了重复元素的数组，如果输入数组为NULL，则返回NULL。
notice
仅支持向量化引擎中使用
example
mysql> set enable_vectorized_engine=true;
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, 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, NULL] |
+------+------------------------------------------+---------------------------+keywords
ARRAY, DISTINCT, ARRAY_DISTINCT