| --- |
| { |
| "title": "ARRAY_DIFFERENCE", |
| "language": "en" |
| } |
| --- |
| |
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| |
| ## array_difference |
| |
| array_difference |
| |
| ### description |
| |
| #### Syntax |
| |
| `ARRAY<T> array_difference(ARRAY<T> arr)` |
| |
| Calculates the difference between adjacent array elements. |
| Returns an array where the first element will be 0, the second is the difference between a[1] - a[0]. |
| need notice that NULL will be return NULL |
| |
| ### example |
| |
| ``` |
| 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 |
| |
