JSON_ARRAY_LENGTH()
JSON_ARRAY_LENGTH(arrayval JSON)
arrayval
SELECT JSON_ARRAY_LENGTH('[4, 7, 10, 11, 14, {"vegetables":"spinach","fruits":"melon"}, {"a":"b"}]');
+-------+ | f | +-------+ | 7 | +-------+
SELECT JSON_ARRAY_LENGTH('[1, 2, [3, 4]]');
+-------+ | f | +-------+ | 3 | +-------+
SELECT JSON_ARRAY_LENGTH('[]');
+-------+ | f | +-------+ | 0 | +-------+