ARRAY_DISTINCT
描述
返回去除了重复元素的数组，如果输入数组为NULL，则返回NULL。
语法
ARRAY_DISTINCT(<arr> )
参数
| 参数 | 说明 |
|---|---|
<arr> | 可能包含要删除的重复元素的数组 |
返回值
返回去除了重复元素的数组。特殊情况：
- 如果输入数组为NULL，则返回NULL。
举例
CREATE TABLE array_test (
k1 INT,
k2 ARRAY<INT>
)
duplicate key (k1)
distributed by hash(k1) buckets 1
properties(
'replication_num' = '1'
);
INSERT INTO array_test VALUES
(1, [1, 2, 3, 4, 5]),
(2, [6, 7, 8]),
(3, []),
(4, NULL),
(5, [1, 2, 3, 4, 5, 4, 3, 2, 1]),
(6, [1, 2, 3, NULL]),
(7, [1, 2, 3, NULL, NULL]);
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] |
+------+-----------------------------+---------------------------+
CREATE TABLE array_test01 (
k1 INT,
k2 ARRAY<VARCHAR>
)
duplicate key (k1)
distributed by hash(k1) buckets 1
properties(
'replication_num' = '1'
);
INSERT INTO array_test01 VALUES
(1, ['a', 'b', 'c', 'd', 'e']),
(2, ['f', 'g', 'h']),
(3, ['']),
(3, [NULL]),
(5, ['a', 'b', 'c', 'd', 'e', 'a', 'b', 'c']),
(6, NULL),
(7, ['a', 'b', NULL]),
(8, ['a', 'b', NULL, NULL]);
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] |
+------+------------------------------------------+---------------------------+
