array_first_index
array_first_index
array_first_index
description
Syntax
ARRAY<T> array_first_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。 返回第一个使得 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。
array_first_index(x->x>1, array1);
array_first_index(x->(x%2 = 0), array1);
array_first_index(x->(abs(x)-1), array1);
array_first_index((x,y)->(x = y), array1, array2);
example
mysql> select array_first_index(x->x+1>3, [2, 3, 4]);
+-------------------------------------------------------------------+
| array_first_index(array_map([x] -> x(0) + 1 > 3, ARRAY(2, 3, 4))) |
+-------------------------------------------------------------------+
| 2 |
+-------------------------------------------------------------------+
mysql> select array_first_index(x -> x is null, [null, 1, 2]);
+----------------------------------------------------------------------+
| array_first_index(array_map([x] -> x(0) IS NULL, ARRAY(NULL, 1, 2))) |
+----------------------------------------------------------------------+
| 1 |
+----------------------------------------------------------------------+
mysql> select array_first_index(x->power(x,2)>10, [1, 2, 3, 4]);
+---------------------------------------------------------------------------------+
| array_first_index(array_map([x] -> power(x(0), 2.0) > 10.0, ARRAY(1, 2, 3, 4))) |
+---------------------------------------------------------------------------------+
| 4 |
+---------------------------------------------------------------------------------+
mysql> select col2, col3, array_first_index((x,y)->x>y, col2, col3) from array_test;
+--------------+--------------+---------------------------------------------------------------------+
| col2 | col3 | array_first_index(array_map([x, y] -> x(0) > y(1), `col2`, `col3`)) |
+--------------+--------------+---------------------------------------------------------------------+
| [1, 2, 3] | [3, 4, 5] | 0 |
| [1, NULL, 2] | [NULL, 3, 1] | 3 |
| [1, 2, 3] | [9, 8, 7] | 0 |
| NULL | NULL | 0 |
+--------------+--------------+---------------------------------------------------------------------+
keywords
ARRAY,FIRST_INDEX,ARRAY_FIRST_INDEX
