14.17.2 Functions That Create JSON Values

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MySQL 8.4 Reference Manual Including MySQL NDB Cluster 8.4

14.17.2 Functions That Create JSON Values

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

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 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”.