COLLECT_LIST

description

Syntax

ARRAY<T> collect_list(expr)

Returns an array consisting of all values in expr within the group. The order of elements in the array is non-deterministic. NULL values are excluded.

notice

  1. Only supported in vectorized engine

example

  1. mysql> set enable_vectorized_engine=true;
  3. mysql> select k1,k2,k3 from collect_test order by k1;
  4. +------+------------+-------+
  5. | k1   | k2         | k3    |
  6. +------+------------+-------+
  7. |    1 | 2022-07-05 | hello |
  8. |    2 | 2022-07-04 | NULL  |
  9. |    2 | 2022-07-04 | hello |
  10. |    3 | NULL       | world |
  11. |    3 | NULL       | world |
  12. +------+------------+-------+
  14. mysql> select k1,collect_list(k2),collect_list(k3) from collect_test group by k1 order by k1;
  15. +------+--------------------------+--------------------+
  16. | k1   | collect_list(`k2`)       | collect_list(`k3`) |
  17. +------+--------------------------+--------------------+
  18. |    1 | [2022-07-05]             | [hello]            |
  19. |    2 | [2022-07-04, 2022-07-04] | [hello]            |
  20. |    3 | NULL                     | [world, world]     |
  21. +------+--------------------------+--------------------+

keywords

COLLECT_LIST,COLLECT_SET,ARRAY