Json_keys

Description

Syntax

ARRAY<STRING> json_keys(JSON, [VARCHAR path])

Returns the keys from the top-level value of a JSON object as a JSON array, or, if a path argument is given, the top-level keys from the selected path. Returns NULL if any argument is NULL, the json_doc argument is not an object, or path, if given, does not locate an object. An error occurs if the json_doc argument is not a valid JSON document or the path argument is not a valid path expression

Note:

The result array is empty if the selected object is empty. If the top-level value has nested subobjects, the return value does not include keys from those subobjects.

Example

  2. mysql> SELECT JSON_KEYS('{"a": 1, "b": {"c": 30}}');
  3. +-----------------------------------------------------+
  4. | json_keys(cast('{"a": 1, "b": {"c": 30}}' as JSON)) |
  5. +-----------------------------------------------------+
  6. | ["a", "b"]                                          |
  7. +-----------------------------------------------------+
  8. 1 row in set (0.35 sec)
  10. mysql> SELECT JSON_KEYS('{"a": 1, "b": {"c": 30}}', '$.b');
  11. +------------------------------------------------------------+
  12. | json_keys(cast('{"a": 1, "b": {"c": 30}}' as JSON), '$.b') |
  13. +------------------------------------------------------------+
  14. | ["c"]                                                      |
  15. +------------------------------------------------------------+
  16. 1 row in set (0.07 sec)
  18. mysql> SELECT JSON_KEYS('{}');
  19. +-------------------------------+
  20. | json_keys(cast('{}' as JSON)) |
  21. +-------------------------------+
  22. | []                            |
  23. +-------------------------------+
  24. 1 row in set (0.07 sec)
  26. mysql> SELECT JSON_KEYS('[1,2]');
  27. +----------------------------------+
  28. | json_keys(cast('[1,2]' as JSON)) |
  29. +----------------------------------+
  30. | NULL                             |
  31. +----------------------------------+
  32. 1 row in set (0.07 sec)
  34. mysql> SELECT JSON_KEYS('[]');
  35. +-------------------------------+
  36. | json_keys(cast('[]' as JSON)) |
  37. +-------------------------------+
  38. | NULL                          |
  39. +-------------------------------+
  40. 1 row in set (0.07 sec)

Keywords

json,json_keys