This is a set of three JSON functions, which returns the value of a given key in a JSON map or an element in a JSON array. Maps are in the form:

{"a": 1, "b": 2, "c": 3}

• JSON_EXTRACT_DOUBLE is for all numeric data (equivalent to the ::% JSON operator). JavaScript has only one numeric type.

• JSON_EXTRACT_STRING is for all text and binary types (equivalent to the ::$ JSON operator).

• JSON_EXTRACT_JSON is for all valid JavaScript types, including true, false, JSON maps, and lists.

  Info

  For more info on JSON operators ::, ::$, and ::%, see Accessing Fields in a JSON Object.

JSON_EXTRACT_<type>(json, keypath)

Arguments

• json: a valid JSON map, or the name of a JSON column.
• keypath: The path to the key to extract (comma-separated list of dictionary keys or zero-indexed array positions).

Return Value

• The extracted element.
• SQL NULL if json is not a valid JSON array, or if keyname does not exist.

Examples

mysql> select json_extract_double('{"a":1, "b":2, "c": [3,4,5]}', 'b') as get_b;
+-------+
| get_b |
+-------+
|     2 |
+-------+

mysql> select json_extract_json('{"a":1, "b":2, "c": [3,4,5]}', 'c') as get_c;
+---------+
| get_c   |
+---------+
| [3,4,5] |
+---------+

mysql> select json_extract_json('{"a":1, "b":2, "c": [3,4,5]}', 'c', 1) as get_c;
+-------+
| get_c |
+-------+
| 4     |
+-------+

mysql> select json_extract_json('{"a":1, "b":2, "c": [3,4,5]}', 'z') as get_z;
+-------+
| get_z |
+-------+
| NULL  |
+-------+

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