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JSON_EXTRACT_<type>
This is a set of three JSON functions, which returns the value of a given key in a JSON map. Maps are in the form:
{"a": 1, "b": 2, "c": 3}
JSON_EXTRACT_DOUBLE
is for all numeric data. Javascript has only one numeric type.JSON_EXTRACT_STRING
is for all text and binary types.JSON_EXTRACT_JSON
is for all valid Javascript types, includingtrue
,false
, JSON maps, and lists.
JSON_EXTRACT_<type>(json, keyname)
Arguments
- json: a valid JSON map, or the name of a JSON column.
- keyname: the named key to extract.
Return Type
- 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]}', 'z') as get_z;
+-------+
| get_z |
+-------+
| NULL |
+-------+