JSON_LENGTH
Computes the length of a JSON map or array.
JSON_LENGTH(json)
Arguments
json: a valid JSON array or map.
Return Value
the length as an integer
SQL NULL if json is not a valid JSON array or map
Examples
SELECT JSON_LENGTH('true');
+---------------------+
| JSON_LENGTH('true') |
+---------------------+
| NULL |
+---------------------+
SELECT JSON_LENGTH('[1,2,3]');
+------------------------+
| JSON_LENGTH('[1,2,3]') |
+------------------------+
| 3 |
+------------------------+
SELECT JSON_LENGTH('{"a": 1, "b": 2}');
+---------------------------------+
| JSON_LENGTH('{"a": 1, "b": 2}') |
+---------------------------------+
| 2 |
+---------------------------------+
Notice
A JSON or Javascript null value is distinct from SQL NULL.