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MySQL5.7的JSON基础操纵
MySQL从5.7版本最先就支撑JSON花样的数据，操纵用起来挺轻易的。
建表
在新建表时字段范例能够直接设置为json范例，比方我们建立一张表：
mysql> CREATE TABLE `test_user`(`id` INT PRIMARY KEY AUTO_INCREMENT, `name` VARCHAR(50) NOT NULL, `info` JSON);
json范例字段能够为NULL
插进去数据：
mysql> INSERT INTO test_user(`name`, `info`) VALUES('xiaoming','{"sex": 1, "age": 18, "nick_name": "小萌"}');
json范例的字段必需时一个有用的json字符串
能够运用JSON_OBJECT()函数组织json对象：
mysql> INSERT INTO test_user(`name`, `info`) VALUES('xiaohua', JSON_OBJECT("sex", 0, "age", 17));
运用JSON_ARRAY()函数组织json数组：
mysql> INSERT INTO test_user(`name`, `info`) VALUES('xiaozhang', JSON_OBJECT("sex", 1, "age", 19, "tag", JSON_ARRAY(3,5,90)));
如今检察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，能够用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)
也能够直接运用操纵符->>
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)
固然属性也能够作为查询前提
mysql> select name, info->>'$.nick_name' from test_user where info->'$.nick_name'='小萌'; +----------+----------------------+ | name | info->>'$.nick_name' | +----------+----------------------+ | xiaoming | 小萌 | +----------+----------------------+ 1 row in set (0.05 sec)
值得一提的是，能够经由过程假造列对JSON范例的指定属性举行疾速查询。
建立假造列:
mysql> ALTER TABLE `test_user` ADD `nick_name` VARCHAR(50) GENERATED ALWAYS AS (info->>'$.nick_name') VIRTUAL;
注重用操纵符->>
运用时和一般范例的列查询是一样:
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
运用JSON_INSERT()插进去新值，但不会掩盖已存在的值
mysql> UPDATE test_user SET info = JSON_INSERT(info, '$.sex', 1, '$.nick_name', '小花') where id=2;
看下效果
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)
运用JSON_SET()插进去新值，并掩盖已存在的值
mysql> UPDATE test_user SET info = JSON_INSERT(info, '$.sex', 0, '$.nick_name', '小张') where id=3;
看下效果
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)
运用JSON_REPLACE()只替代存在的值
mysql> UPDATE test_user SET info = JSON_REPLACE(info, '$.sex', 1, '$.tag', '[1,2,3]') where id=2;
看下效果
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)
能够看到tag没有更新进去
删除
运用JSON_REMOVE()删除JSON元素
mysql> UPDATE test_user SET info = JSON_REMOVE(info, '$.sex', '$.tag') where id=1;
看下效果
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)
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