array_last_index

SinceVersion 2.0

array_last_index

description

Syntax

ARRAY<T> array_last_index(lambda, ARRAY<T> array1, ...)

使用lambda表达式作为输入参数，对其他输入ARRAY参数的内部数据进行相应的表达式计算。 返回最后一个使得 lambda(array1[i], ...) 返回值不为 0 的索引。如果没找到满足此条件的索引，则返回 0。

在lambda表达式中输入的参数为1个或多个，所有输入的array的元素数量必须一致。在lambda中可以执行合法的标量函数，不支持聚合函数等。

  1. array_last_index(x->x>1, array1);
  2. array_last_index(x->(x%2 = 0), array1);
  3. array_last_index(x->(abs(x)-1), array1);
  4. array_last_index((x,y)->(x = y), array1, array2);

example

  1. mysql> select array_last_index(x->x+1>3, [2, 3, 4]);
  2. +-------------------------------------------------------------------+
  3. | array_last_index(array_map([x] -> x(0) + 1 > 3, ARRAY(2, 3, 4))) |
  4. +-------------------------------------------------------------------+
  5. |                                                                 3 |
  6. +-------------------------------------------------------------------+
  8. mysql> select array_last_index(x -> x is null, [null, 1, 2]);
  9. +----------------------------------------------------------------------+
  10. | array_last_index(array_map([x] -> x(0) IS NULL, ARRAY(NULL, 1, 2))) |
  11. +----------------------------------------------------------------------+
  12. |                                                                    1 |
  13. +----------------------------------------------------------------------+
  15. mysql> select array_last_index(x->power(x,2)>10, [1, 2, 3, 4]);
  16. +---------------------------------------------------------------------------------+
  17. | array_last_index(array_map([x] -> power(x(0), 2.0) > 10.0, ARRAY(1, 2, 3, 4))) |
  18. +---------------------------------------------------------------------------------+
  19. |                                                                               4 |
  20. +---------------------------------------------------------------------------------+
  22. mysql> select c_array1, c_array2, array_last_index((x,y)->x>y, c_array1, c_array2) from array_index_table order by id;
  23. +-----------------+-------------------------+----------------------------------------------------------------------+
  24. | c_array1        | c_array2                | array_last_index(array_map([x, y] -> x > y, `c_array1`, `c_array2`)) |
  25. +-----------------+-------------------------+----------------------------------------------------------------------+
  26. | [1, 2, 3, 4, 5] | [10, 20, -40, 80, -100] |                                                                    5 |
  27. | [6, 7, 8]       | [10, 12, 13]            |                                                                    0 |
  28. | [1]             | [-100]                  |                                                                    1 |
  29. | [1, NULL, 2]    | [NULL, 3, 1]            |                                                                    3 |
  30. | []              | []                      |                                                                    0 |
  31. | NULL            | NULL                    |                                                                    0 |
  32. +-----------------+-------------------------+----------------------------------------------------------------------+

keywords

ARRAY,FIRST_INDEX,array_last_index