MySQL操作之JSON数据类型操作详解

CREATE TABLE table_name (
  id INT NOT NULL AUTO_INCREMENT, 
  json_col JSON,
  PRIMARY KEY(id)
);

INSERT INTO
  table_name (json_col) 
VALUES
  ('{"City": "Galle", "Description": "Best damn city in the world"}');
  

INSERT INTO table(col) 
VALUES('{"opening":"Sicilian","variations":["pelikan","dragon","najdorf"]}');

UPDATE myjson SET dict=JSON_ARRAY_APPEND(dict,'$.variations','scheveningen') WHERE id = 2;

SELECT * FROM myjson

+----+-----------------------------------------------------------------------------------------+
| id | dict                                          |
+---+-----------------------------------------------------------------------------------------+
| 2 | {"opening": "Sicilian", "variations": ["pelikan", "dragon", "najdorf", "scheveningen"]} |
+----+-----------------------------------------------------------------------------------------+
1 row in set (0.00 sec)

mysql> CREATE TABLE jemp (
  ->   c JSON,
  ->   g INT GENERATED ALWAYS AS (c->"$.id"),
  ->   INDEX i (g)
  -> );
Query OK, 0 rows affected (0.28 sec)

mysql> INSERT INTO jemp (c) VALUES
   >  ('{"id": "1", "name": "Fred"}'), ('{"id": "2", "name": "Wilma"}'),
   >  ('{"id": "3", "name": "Barney"}'), ('{"id": "4", "name": "Betty"}');
Query OK, 4 rows affected (0.04 sec)
Records: 4 Duplicates: 0 Warnings: 0

mysql> SELECT c->>"$.name" AS name
   >   FROM jemp WHERE g > 2;
+--------+
| name  |
+--------+
| Barney |
| Betty |
+--------+
2 rows in set (0.00 sec)

mysql> EXPLAIN SELECT c->>"$.name" AS name
   >  FROM jemp WHERE g > 2\G
*************************** 1. row ***************************
      id: 1
 select_type: SIMPLE
    table: jemp
  partitions: NULL
     type: range
possible_keys: i
     key: i
   key_len: 5
     ref: NULL
     rows: 2
   filtered: 100.00
    Extra: Using where
1 row in set, 1 warning (0.00 sec)

mysql> SHOW WARNINGS\G
*************************** 1. row ***************************
 Level: Note
  Code: 1003
Message: /* select#1 */ select json_unquote(json_extract(`test`.`jemp`.`c`,'$.name'))
AS `name` from `test`.`jemp` where (`test`.`jemp`.`g` > 2)
1 row in set (0.00 sec)

SELECT CAST('[1,2,3]' as JSON) ;
SELECT CAST('{"opening":"Sicilian","variations":["pelikan","dragon","najdorf"]}' as JSON);