JSON字段List成员检查
文档
- https://dev.mysql.com/doc/refman/8.0/en/json.html
- https://dev.mysql.com/doc/refman/8.0/en/json-search-functions.html
方法
JSON_CONTAINS(target, candidate[, path])
value MEMBER OF(json_array)查询示例
mysql> set @list = JSON_ARRAY(1, 2);
Query OK, 0 rows affected (0.01 sec)
mysql> select 1 MEMBER OF(@list);
+--------------------+
| 1 MEMBER OF(@list) |
+--------------------+
| 1 |
+--------------------+
1 row in set (0.00 sec)
mysql> SELECT JSON_CONTAINS(@list, '1');
+---------------------------+
| JSON_CONTAINS(@list, '1') |
+---------------------------+
| 1 |
+---------------------------+
1 row in set (0.01 sec)MySQL中JSON字段操作
Mysql 自5.7之后增加了很多函数用于处理Json字串。方便实用。
基本改变
Json数组：
["abc", 10, null, true, false]Json对象：
{"k1": "value", "k2": 10}JSON数组元素和JSON对象键值内允许嵌套
Json函数
JSON_TYPE()：返回json字串类型
mysql> SELECT JSON_TYPE('["a", "b", 1]');
+----------------------------+
| JSON_TYPE('["a", "b", 1]') |
+----------------------------+
| ARRAY |
+----------------------------+
mysql> SELECT JSON_TYPE('"hello"');
+----------------------+
| JSON_TYPE('"hello"') |
+----------------------+
| STRING |
+----------------------+
mysql> SELECT JSON_TYPE('hello');
ERROR 3146 (22032): Invalid data type for JSON data in argument 1
to function json_type; a JSON string or JSON type is required.MySQL使用utf8mb4字符集和utf8mb4_bin排序规则处理JSON上下文中使用的字符串 。其他字符集中的字符串将utf8mb4根据需要转换。（对于ascii或 utf8字符集中的字符串，无需进行转换，因为ascii和utf8是的子集utf8mb4。一般将数据库字符集设置为utf8mb4）
JSON_ARRAY()：将数值包装为json数组
mysql> SELECT JSON_ARRAY('a', 1, NOW());
+----------------------------------------+
| JSON_ARRAY('a', 1, NOW()) |
+----------------------------------------+
| ["a", 1, "2015-07-27 09:43:47.000000"] |
+----------------------------------------+JSON_OBJECT()：将数值包装为json对象
mysql> SELECT JSON_OBJECT('key1', 1, 'key2', 'abc');
+---------------------------------------+
| JSON_OBJECT('key1', 1, 'key2', 'abc') |
+---------------------------------------+
| {"key1": 1, "key2": "abc"} |
+---------------------------------------+JSON_MERGE()：将多个json合并为一个
mysql> SELECT JSON_MERGE('["a", 1]', '{"key": "value"}');
+--------------------------------------------+
| JSON_MERGE('["a", 1]', '{"key": "value"}') |
+--------------------------------------------+
| ["a", 1, {"key": "value"}] |
+--------------------------------------------+Json字符串中的key-value访问
使用column-path运算符 ->得到字段中json某个key的值，但是值中的"""和"\"都会显示，如果不想显示，使用->>。
#创建表
CREATE TABLE facts (ids JSON);
#插入数据 这里要注意是否启用了服务器SQL模式，插入数据时要注意特殊符号
INSERT INTO facts VALUES (JSON_OBJECT('mascot', 'Our mascot is a dolphin named "Sakila".'));
#查看数据
mysql> select ids from facts;
+---------------------------------------------------------+
| ids |
+---------------------------------------------------------+
| {"mascot": "Our mascot is a dolphin named \"Sakila\"."} |
+---------------------------------------------------------+
1 row in set (0.00 sec)
mysql> SELECT ids->'$.mascot' FROM facts;
+---------------------------------------------+
| ids->'$.mascot' |
+---------------------------------------------+
| "Our mascot is a dolphin named \"Sakila\"." |
+---------------------------------------------+
1 row in set (0.00 sec)
mysql> SELECT ids->>'$.mascot' FROM facts;
+-----------------------------------------+
| ids->>'$.mascot' |
+-----------------------------------------+
| Our mascot is a dolphin named "Sakila". |
+-----------------------------------------+
#注意，这里访问json字段key使用单引号还是双引号取决于sql模式读取json字段中某个key的值
SELECT JSON_EXTRACT('{"id": 14, "name": "Aztalan"}', '$.name');
+---------------------------------------------------------+
| JSON_EXTRACT('{"id": 14, "name": "Aztalan"}', '$.name') |
+---------------------------------------------------------+
| "Aztalan" |
+---------------------------------------------------------+
#去除值双引号
mysql> SELECT JSON_UNQUOTE(JSON_EXTRACT('{"id": 14, "name": "Aztalan"}', '$.name'));
+-----------------------------------------------------------------------+
| JSON_UNQUOTE(JSON_EXTRACT('{"id": 14, "name": "Aztalan"}', '$.name')) |
+-----------------------------------------------------------------------+
| Aztalan |
+-----------------------------------------------------------------------+小结：
| ‘$.*’ | 返回全部json |
| ‘$.title’ | 返回key=”title”的数据 |
| ‘$**.text’ | 返回所有最底层key=”text”的数据 |
| ‘$.content[*].item1[*]’ | 返回key=content的list的key=item1的list的所有内容 |
官网参考地址
以上为个人经验，希望能给大家一个参考，也希望大家多多支持我们。
