ARRAY_COUNT

array_count

SinceVersion 2.0

array_count

description

array_count(lambda, array1, ...)

Use lambda expressions as input parameters to perform corresponding expression calculations on the internal data of other input ARRAY parameters. Returns the number of elements such that the return value of lambda(array1[i], ...) is not 0. Returns 0 if no element is found that satisfies this condition.

There are one or more parameters are input in the lambda expression, which must be consistent with the number of input array columns later.The number of elements of all input arrays must be the same. Legal scalar functions can be executed in lambda, aggregate functions, etc. are not supported.

array_count(x->x, array1);
array_count(x->(x%2 = 0), array1);
array_count(x->(abs(x)-1), array1);
array_count((x,y)->(x = y), array1, array2);

notice

Only supported in vectorized engine

example

mysql> select array_count(x -> x, [0, 1, 2, 3]);
+--------------------------------------------------------+
| array_count(array_map([x] -> x(0), ARRAY(0, 1, 2, 3))) |
+--------------------------------------------------------+
|                                                      3 |
+--------------------------------------------------------+
1 row in set (0.00 sec)

mysql> select array_count(x -> x > 2, [0, 1, 2, 3]);
+------------------------------------------------------------+
| array_count(array_map([x] -> x(0) > 2, ARRAY(0, 1, 2, 3))) |
+------------------------------------------------------------+
|                                                          1 |
+------------------------------------------------------------+
1 row in set (0.01 sec)

mysql> select array_count(x -> x is null, [null, null, null, 1, 2]);
+----------------------------------------------------------------------------+
| array_count(array_map([x] -> x(0) IS NULL, ARRAY(NULL, NULL, NULL, 1, 2))) |
+----------------------------------------------------------------------------+
|                                                                          3 |
+----------------------------------------------------------------------------+
1 row in set (0.01 sec)

mysql> select array_count(x -> power(x,2)>10, [1, 2, 3, 4, 5]);
+------------------------------------------------------------------------------+
| array_count(array_map([x] -> power(x(0), 2.0) > 10.0, ARRAY(1, 2, 3, 4, 5))) |
+------------------------------------------------------------------------------+
|                                                                            2 |
+------------------------------------------------------------------------------+
1 row in set (0.01 sec)

mysql> select *, array_count((x, y) -> x>y, c_array1, c_array2) from array_test;
+------+-----------------+-------------------------+-----------------------------------------------------------------------+
| id   | c_array1        | c_array2                | array_count(array_map([x, y] -> x(0) > y(1), `c_array1`, `c_array2`)) |
+------+-----------------+-------------------------+-----------------------------------------------------------------------+
|    1 | [1, 2, 3, 4, 5] | [10, 20, -40, 80, -100] |                                                                     2 |
|    2 | [6, 7, 8]       | [10, 12, 13]            |                                                                     0 |
|    3 | [1]             | [-100]                  |                                                                     1 |
|    4 | [1, NULL, 2]    | [NULL, 3, 1]            |                                                                     1 |
|    5 | []              | []                      |                                                                     0 |
|    6 | NULL            | NULL                    |                                                                     0 |
+------+-----------------+-------------------------+-----------------------------------------------------------------------+
6 rows in set (0.02 sec)

keywords

ARRAY, COUNT, ARRAY_COUNT