array_difference
description
Syntax
ARRAY<T> array_difference(ARRAY<T> arr)计算相邻数组元素之间的差异。返回一个数组，其中第一个元素将为0，第二个元素是[1]-a[0]之间的差值。 注意若 NULL 值存在，返回结果为NULL
notice
仅支持向量化引擎中使用
example
mysql> set enable_vectorized_engine=true;
mysql> select *,array_difference(k2) from array_type_table;
+------+-----------------------------+---------------------------------+
| k1 | k2 | array_difference(`k2`) |
+------+-----------------------------+---------------------------------+
| 0 | [] | [] |
| 1 | [NULL] | [NULL] |
| 2 | [1, 2, 3] | [0, 1, 1] |
| 3 | [1, NULL, 3] | [0, NULL, NULL] |
| 4 | [0, 1, 2, 3, NULL, 4, 6] | [0, 1, 1, 1, NULL, NULL, 2] |
| 5 | [1, 2, 3, 4, 5, 4, 3, 2, 1] | [0, 1, 1, 1, 1, -1, -1, -1, -1] |
| 6 | [6, 7, 8] | [0, 1, 1] |
+------+-----------------------------+---------------------------------+
keywords
ARRAY, DIFFERENCE, ARRAY_DIFFERENCE