14.17.2 Functions That Create JSON Values

The functions listed in this section compose JSON values from component elements.

• JSON_ARRAY([val[, val] ...])

  Evaluates a (possibly empty) list of values and returns a JSON array containing those values.

  mysql> SELECT JSON_ARRAY(1, "abc", NULL, TRUE, CURTIME());
  +---------------------------------------------+
  | JSON_ARRAY(1, "abc", NULL, TRUE, CURTIME()) |
  +---------------------------------------------+
  | [1, "abc", null, true, "11:30:24.000000"]   |
  +---------------------------------------------+

• JSON_DUALITY_OBJECT([table_annotations] json_duality_key_value_pairs)

  This function returns a JSON duality object for use in CREATE JSON DUALITY VIEW or ALTER JSON DUALITY VIEW. Attempting to invoke it in any other context results in an error.

  See Section 27.7, “JSON Duality Views”, for more examples, as well as the descriptions of the CREATE JSON DUALITY VIEW and ALTER JSON DUALITY VIEW statements.

• JSON_OBJECT([key, val[, key, val] ...])

  Evaluates a (possibly empty) list of key-value pairs and returns a JSON object containing those pairs. An error occurs if any key name is NULL or the number of arguments is odd.

  mysql> SELECT JSON_OBJECT('id', 87, 'name', 'carrot');
  +-----------------------------------------+
  | JSON_OBJECT('id', 87, 'name', 'carrot') |
  +-----------------------------------------+
  | {"id": 87, "name": "carrot"}            |
  +-----------------------------------------+

• JSON_QUOTE(string)

  Quotes a string as a JSON value by wrapping it with double quote characters and escaping interior quote and other characters, then returning the result as a utf8mb4 string. Returns NULL if the argument is NULL.

  This function is typically used to produce a valid JSON string literal for inclusion within a JSON document.

  Certain special characters are escaped with backslashes per the escape sequences shown in Table 14.23, “JSON_UNQUOTE() Special Character Escape Sequences”.

  mysql> SELECT JSON_QUOTE('null'), JSON_QUOTE('"null"');
  +--------------------+----------------------+
  | JSON_QUOTE('null') | JSON_QUOTE('"null"') |
  +--------------------+----------------------+
  | "null"             | "\"null\""           |
  +--------------------+----------------------+
  mysql> SELECT JSON_QUOTE('[1, 2, 3]');
  +-------------------------+
  | JSON_QUOTE('[1, 2, 3]') |
  +-------------------------+
  | "[1, 2, 3]"             |
  +-------------------------+

You can also obtain JSON values by casting values of other types to the JSON type using CAST(value AS JSON); see Converting between JSON and non-JSON values, for more information.

Two aggregate functions generating JSON values are available. JSON_ARRAYAGG() returns a result set as a single JSON array, and JSON_OBJECTAGG() returns a result set as a single JSON object. For more information, see Section 14.19, “Aggregate Functions”.