12.17.2 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_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 12.23, “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 (MySQL 5.7.22 and later). 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 12.19, “Aggregate Functions”.