MySQL从5.7版本开始就支持JSON格式的数据,操作用起来挺方便的。
建表
在新建表时字段类型可以直接设置为json类型,比如我们创建一张表:
mysql> CREATE TABLE `test_user`(`id` INT PRIMARY KEY AUTO_INCREMENT, `name` VARCHAR(50) NOT NULL, `info` JSON);
json类型字段可以为NULL
插入数据:
mysql> INSERT INTO test_user(`name`, `info`) VALUES('xiaoming','{"sex": 1, "age": 18, "nick_name": "小萌"}');
json类型的字段必须时一个有效的json字符串
可以使用JSON_OBJECT()函数构造json对象:
mysql> INSERT INTO test_user(`name`, `info`) VALUES('xiaohua', JSON_OBJECT("sex", 0, "age", 17));
使用JSON_ARRAY()函数构造json数组:
mysql> INSERT INTO test_user(`name`, `info`) VALUES('xiaozhang', JSON_OBJECT("sex", 1, "age", 19, "tag", JSON_ARRAY(3,5,90)));
现在查看test_user
表中的数据:
mysql> select * from test_user;
+----+-----------+--------------------------------------------+
| id | name | info |
+----+-----------+--------------------------------------------+
| 1 | xiaoming | {"age": 18, "sex": 1, "nick_name": "小萌"} |
| 2 | xiaohua | {"age": 17, "sex": 0} |
| 3 | xiaozhang | {"age": 19, "sex": 1, "tag": [3, 5, 90]} |
+----+-----------+--------------------------------------------+
3 rows in set (0.04 sec)
查询
表达式: 对象为json列->'$.键'
, 数组为json列->'$.键[index]'
mysql> select name, info->'$.nick_name', info->'$.sex', info->'$.tag[0]' from test_user;
+-----------+---------------------+---------------+------------------+
| name | info->'$.nick_name' | info->'$.sex' | info->'$.tag[0]' |
+-----------+---------------------+---------------+------------------+
| xiaoming | "小萌" | 1 | NULL |
| xiaohua | NULL | 0 | NULL |
| xiaozhang | NULL | 1 | 3 |
+-----------+---------------------+---------------+------------------+
3 rows in set (0.04 sec)
等价于:对象为JSON_EXTRACT(json列 , '$.键')
,数组为JSON_EXTRACT(json列 , '$.键[index]')
mysql> select name, JSON_EXTRACT(info, '$.nick_name'), JSON_EXTRACT(info, '$.sex'), JSON_EXTRACT(info, '$.tag[0]') from test_user;
+-----------+-----------------------------------+-----------------------------+--------------------------------+
| name | JSON_EXTRACT(info, '$.nick_name') | JSON_EXTRACT(info, '$.sex') | JSON_EXTRACT(info, '$.tag[0]') |
+-----------+-----------------------------------+-----------------------------+--------------------------------+
| xiaoming | "小萌" | 1 | NULL |
| xiaohua | NULL | 0 | NULL |
| xiaozhang | NULL | 1 | 3 |
+-----------+-----------------------------------+-----------------------------+--------------------------------+
3 rows in set (0.04 sec)
不过看到上面"小萌"
是带双引号的,这不是我们想要的,可以用JSON_UNQUOTE
函数将双引号去掉
mysql> select name, JSON_UNQUOTE(info->'$.nick_name') from test_user where name='xiaoming';
+----------+-----------------------------------+
| name | JSON_UNQUOTE(info->'$.nick_name') |
+----------+-----------------------------------+
| xiaoming | 小萌 |
+----------+-----------------------------------+
1 row in set (0.05 sec)
也可以直接使用操作符->>
mysql> select name, info->>'$.nick_name' from test_user where name='xiaoming';
+----------+----------------------+
| name | info->>'$.nick_name' |
+----------+----------------------+
| xiaoming | 小萌 |
+----------+----------------------+
1 row in set (0.06 sec)
当然属性也可以作为查询条件
mysql> select name, info->>'$.nick_name' from test_user where info->'$.nick_name'='小萌';
+----------+----------------------+
| name | info->>'$.nick_name' |
+----------+----------------------+
| xiaoming | 小萌 |
+----------+----------------------+
1 row in set (0.05 sec)
值得一提的是,可以通过虚拟列对JSON类型的指定属性进行快速查询。
创建虚拟列:
mysql> ALTER TABLE `test_user` ADD `nick_name` VARCHAR(50) GENERATED ALWAYS AS (info->>'$.nick_name') VIRTUAL;
注意用操作符->>
使用时和普通类型的列查询是一样:
mysql> select name,nick_name from test_user where nick_name='小萌';
+----------+-----------+
| name | nick_name |
+----------+-----------+
| xiaoming | 小萌 |
+----------+-----------+
1 row in set (0.05 sec)
更新
使用JSON_INSERT()
插入新值,但不会覆盖已经存在的值
mysql> UPDATE test_user SET info = JSON_INSERT(info, '$.sex', 1, '$.nick_name', '小花') where id=2;
看下结果
mysql> select * from test_user where id=2;
+----+---------+--------------------------------------------+-----------+
| id | name | info | nick_name |
+----+---------+--------------------------------------------+-----------+
| 2 | xiaohua | {"age": 17, "sex": 0, "nick_name": "小花"} | 小花 |
+----+---------+--------------------------------------------+-----------+
1 row in set (0.06 sec)
使用JSON_SET()
插入新值,并覆盖已经存在的值
mysql> UPDATE test_user SET info = JSON_SET(info, '$.sex', 0, '$.nick_name', '小张') where id=3;
看下结果
mysql> select * from test_user where id=3;
+----+-----------+---------------------------------------------------------------+-----------+
| id | name | info | nick_name |
+----+-----------+---------------------------------------------------------------+-----------+
| 3 | xiaozhang | {"age": 19, "sex": 1, "tag": [3, 5, 90], "nick_name": "小张"} | 小张 |
+----+-----------+---------------------------------------------------------------+-----------+
1 row in set (0.06 sec)
使用JSON_REPLACE()
只替换存在的值
mysql> UPDATE test_user SET info = JSON_REPLACE(info, '$.sex', 1, '$.tag', '[1,2,3]') where id=2;
看下结果
mysql> select * from test_user where id=2;
+----+---------+--------------------------------------------+-----------+
| id | name | info | nick_name |
+----+---------+--------------------------------------------+-----------+
| 2 | xiaohua | {"age": 17, "sex": 1, "nick_name": "小花"} | 小花 |
+----+---------+--------------------------------------------+-----------+
1 row in set (0.06 sec)
可以看到tag没有更新进去
删除
使用JSON_REMOVE()
删除JSON元素
mysql> UPDATE test_user SET info = JSON_REMOVE(info, '$.sex', '$.tag') where id=1;
看下结果
mysql> select * from test_user where id=1;
+----+----------+----------------------------------+-----------+
| id | name | info | nick_name |
+----+----------+----------------------------------+-----------+
| 1 | xiaoming | {"age": 18, "nick_name": "小萌"} | 小萌 |
+----+----------+----------------------------------+-----------+
1 row in set (0.05 sec)
最后从MySQL的官方网站查看帮助文档:http://dev.mysql.com/doc/refman/5.7/en/json.html
😎
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