reverse

description

Syntax

VARCHAR reverse(VARCHAR str) ARRAY<T> reverse(ARRAY<T> arr)

将字符串或数组反转，返回的字符串或者数组的顺序和原来的顺序相反。

notice

对于数组类型，仅支持向量化引擎中使用

example

mysql> SELECT REVERSE('hello');
+------------------+
| REVERSE('hello') |
+------------------+
| olleh            |
+------------------+
1 row in set (0.00 sec)
mysql> SELECT REVERSE('你好');
+------------------+
| REVERSE('你好')   |
+------------------+
| 好你              |
+------------------+
1 row in set (0.00 sec)
mysql> set enable_vectorized_engine=true;
mysql> select k1, k2, reverse(k2) from array_test order by k1;
+------+-----------------------------+-----------------------------+
| k1   | k2                          | reverse(`k2`)               |
+------+-----------------------------+-----------------------------+
|  1   | [1, 2, 3, 4, 5]             | [5, 4, 3, 2, 1]             |
|  2   | [6, 7, 8]                   | [8, 7, 6]                   |
|  3   | []                          | []                          |
|  4   | NULL                        | NULL                        |
|  5   | [1, 2, 3, 4, 5, 4, 3, 2, 1] | [1, 2, 3, 4, 5, 4, 3, 2, 1] |
|  6   | [1, 2, 3, NULL]             | [NULL, 3, 2, 1]             |
|  7   | [4, 5, 6, NULL, NULL]       | [NULL, NULL, 6, 5, 4]       |
+------+-----------------------------+-----------------------------+
mysql> select k1, k2, reverse(k2) from array_test01 order by k1;
+------+-----------------------------------+-----------------------------------+
| k1   | k2                                | reverse(`k2`)                     |
+------+-----------------------------------+-----------------------------------+
|  1   | ['a', 'b', 'c', 'd']              | ['d', 'c', 'b', 'a']              |
|  2   | ['e', 'f', 'g', 'h']              | ['h', 'g', 'f', 'e']              |
|  3   | [NULL, 'a', NULL, 'b', NULL, 'c'] | ['c', NULL, 'b', NULL, 'a', NULL] |
|  4   | ['d', 'e', NULL, ' ']             | [' ', NULL, 'e', 'd']             |
|  5   | [' ', NULL, 'f', 'g']             | ['g', 'f', NULL, ' ']             |
+------+-----------------------------------+-----------------------------------+

keywords

REVERSE, ARRAY