ARRAY<K> map_keys(Map<K, V> map)
Extracts the keys of a given map into an ARRAY of the corresponding type.
mysql> select map_keys(map(1, "100", 0.1, 2)); +-------------------------------------------------------------------------------------------------+ | map_keys(map(cast(1 as DECIMALV3(2, 1)), '100', cast(0.1 as DECIMALV3(2, 1)), cast(2 as TEXT))) | +-------------------------------------------------------------------------------------------------+ | [1.0, 0.1] | +-------------------------------------------------------------------------------------------------+ 1 row in set (0.15 sec) mysql> select map_keys(map()); +-----------------+ | map_keys(map()) | +-----------------+ | [] | +-----------------+ 1 row in set (0.12 sec)
MAP, KEYS, MAP_KEYS