MySQL在5.7.8开始对json原生支持,本文将对MySQL中json类型的用法简单说明,希望对你有用。
CREATE TABLE testproject ( `id` int(10) unsigned NOT NULL AUTO_INCREMENT, `skill` JSON NOT NULL, `student` JSON NOT NULL, PRIMARY KEY (`id`) );
查看表结构:
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这样JSON的字段就被创建好了
注:JSON类型不能有默认值。
插入JSON
插入 json 格式的字符串,可以是对象的形式,也可以是数组的形式,
INSERT INTO `testproject` (student, skill) VALUES ('{"id": 1, "name": "ggjg"}', '["java", "go", "vue"]');INSERT INTO `testproject` (student, skill) VALUES ('{"id": 5, "name": "guogege"}', '[]');
插入json时,数据库会对json做校验,不符合json规范就会报错。
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查询JSON:
查询 json 中的数据用 column->path 的形式,其中对象类型 path 这样表示
查询testproject表student字段中json对象id为1的记录:
SELECT * FROM testproject WHERE student->'$.id'= 1;
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查询testproject表student字段中json对象id为1或者5的记录:
SELECT * FROM testproject WHERE student->'$.id' in (1,5);SELECT * FROM testproject WHERE student->'$.id' = 1 or student->'$.id' = 5;
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也可以用函数json_extract:
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column->path方法有限制,数据源必须是表字段,否则就报错:
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以下这样查询,查出来student->'$.name'包含双引号:
SELECT id, student->'$.id', student->'$.name', skill->'$[0]', skill->'$[2]' FROM testproject;
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这不是我们想要的,可以用 JSON_UNQUOTE 函数将双引号去掉,从 MySQL 5.7.13 起也可以通过这个操作符 ->> 这个和 JSON_UNQUOTE 是等价的。
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因为 JSON 不同于字符串,所以如果用字符串和 JSON 字段比较,是不会相等的:
mysql> SELECT * FROM testproject WHERE student = '{"id": 1, "name": "ggjg"}'; Empty set (0.00 sec)
此时可以通过 CAST 将字符串转成 JSON 的形式:
mysql> SELECT * FROM testproject WHERE student = CAST('{"id": 1, "name": "ggjg"}' as JSON); +----+-----------------------+---------------------------+| id | skill | student | +----+-----------------------+---------------------------+| 10 | ["java", "go", "vue"] | {"id": 1, "name": "ggjg"} | +----+-----------------------+---------------------------+1 row in set (0.01 sec)
要特别注意的是,JSON 中的元素搜索是严格区分变量类型的,比如说整型和字符串是严格区分的:
mysql> SELECT * FROM testproject WHERE student->'$.id' = '1'; Empty set (0.00 sec) mysql> mysql> SELECT * FROM testproject WHERE student->'$.id' = 1; +----+-----------------------+---------------------------+ | id | skill | student | +----+-----------------------+---------------------------+ | 10 | ["java", "go", "vue"] | {"id": 1, "name": "ggjg"} | +----+-----------------------+---------------------------+ 1 row in set (0.00 sec)
可以看到搜索字符串 1 和整型 1 的结果是不一样的。
除了用以上 column->path 的形式搜索,还可以用JSON_CONTAINS 函数,但和 column->path 的形式有点相反的是,JSON_CONTAINS 第二个参数是不接受整数的,无论 json 元素是整型还是字符串,否则会出现这个错误:
mysql> SELECT * FROM testproject WHERE JSON_CONTAINS(student, 1, '$.id'); ERROR 3146 (22032): Invalid data type for JSON data in argument 2 to function json_contains; a JSON string or JSON type is required. mysql>
这里必须要使用字符串:
mysql> SELECT * FROM testproject WHERE JSON_CONTAINS(student, '1', '$.id'); +----+-----------------------+---------------------------+| id | skill | student | +----+-----------------------+---------------------------+| 10 | ["java", "go", "vue"] | {"id": 1, "name": "ggjg"} | +----+-----------------------+---------------------------+1 row in set (0.00 sec)
对于数组类型的 JSON 的查询,比如说 skill 中包含有 3 的数据,同样要用 JSON_CONTAINS 函数,同样第二个参数也需要是字符串:
mysql> SELECT * FROM testproject WHERE JSON_CONTAINS(skill, '"go"'); +----+-----------------------+---------------------------+| id | skill | student | +----+-----------------------+---------------------------+| 10 | ["java", "go", "vue"] | {"id": 1, "name": "ggjg"} | +----+-----------------------+---------------------------+1 row in set (0.00 sec) mysql> SELECT * FROM testproject WHERE JSON_CONTAINS(skill, '1'); +----+-----------+------------------------------+| id | skill | student | +----+-----------+------------------------------+| 12 | [1, 2, 3] | {"id": 4, "name": "guogege"} | +----+-----------+------------------------------+1 row in set (0.00 sec)
更新数据
MySQL 并不支持 column->path 的形式进行更新操作。
如果是整个 json 更新的话,和插入时类似的:
mysql> select * from testproject where id = 10; +----+-----------------------+---------------------------+ | id | skill | student | +----+-----------------------+---------------------------+ | 10 | ["java", "go", "vue"] | {"id": 1, "name": "ggjg"} | +----+-----------------------+---------------------------+ 1 row in set (0.00 sec) mysql> UPDATE testproject SET skill = '["js", "java"]' WHERE id = 10; Query OK, 1 row affected (0.01 sec) Rows matched: 1 Changed: 1 Warnings: 0 mysql> select * from testproject where id = 10; +----+----------------+---------------------------+ | id | skill | student | +----+----------------+---------------------------+ | 10 | ["js", "java"] | {"id": 1, "name": "ggjg"} | +----+----------------+---------------------------+ 1 row in set (0.00 sec)
json_array_append和json_array_insert函数使用:
json_array_append是在json后面追加;
json_array_insert是在指定下标插入。
mysql> select * from testproject; +----+----------------+------------------------------+ | id | skill | student | +----+----------------+------------------------------+ | 10 | ["js", "java"] | {"id": 1, "name": "ggjg"} | | 11 | [] | {"id": 5, "name": "guogege"} | | 12 | [1, 2, 3] | {"id": 4, "name": "guogege"} | +----+----------------+------------------------------+ 3 rows in set (0.00 sec) mysql> SELECT json_array_append(skill, '$', 'c') from testproject; +------------------------------------+ | json_array_append(skill, '$', 'c') | +------------------------------------+ | ["js", "java", "c"] | | ["c"] | | [1, 2, 3, "c"] | +------------------------------------+ 3 rows in set (0.00 sec) mysql> SELECT json_array_insert(skill, '$[1]', 'php') from testproject; +-----------------------------------------+ | json_array_insert(skill, '$[1]', 'php') | +-----------------------------------------+ | ["js", "php", "java"] | | ["php"] | | [1, "php", 2, 3] | +-----------------------------------------+ 3 rows in set (0.00 sec) mysql>
json_replace、json_set、json_insert和json_remove函数用法:
json_replace:只替换已经存在的旧值,不存在则忽略;
json_set:替换旧值,并插入不存在的新值;
json_insert:插入新值,但不替换已经存在的旧值;
json_remove() 删除元素。
json_replace:
mysql> select * from testproject; +----+----------------+--------------------------------+ | id | skill | student | +----+----------------+--------------------------------+ | 10 | ["js", "java"] | {"id": 1, "name": "smallsoup"} | | 11 | [] | {"id": 5, "name": "guogege"} | | 12 | [1, 2, 3] | {"id": 4, "name": "guogege"} | +----+----------------+--------------------------------+ 3 rows in set (0.00 sec) mysql> mysql> UPDATE testproject SET student->'$.name' = 'smallsoup' where student->'$.id' = 1; ERROR 1064 (42000): You have an error in your SQL syntax; check the manual that corresponds to your MySQL server versio n for the right syntax to use near '->'$.name' = 'smallsoup' where student->'$.id' = 1' at line 1 mysql> mysql> UPDATE testproject SET student = json_replace(student, '$.name', 'soup') WHERE student->'$.id' = 1; Query OK, 1 row affected (0.01 sec) Rows matched: 1 Changed: 1 Warnings: 0 mysql> select * from testproject; +----+----------------+------------------------------+ | id | skill | student | +----+----------------+------------------------------+ | 10 | ["js", "java"] | {"id": 1, "name": "soup"} | | 11 | [] | {"id": 5, "name": "guogege"} | | 12 | [1, 2, 3] | {"id": 4, "name": "guogege"} | +----+----------------+------------------------------+ 3 rows in set (0.00 sec)
json_set:
mysql> select * from testproject; +----+----------------+------------------------------+| id | skill | student | +----+----------------+------------------------------+| 10 | ["js", "java"] | {"id": 1, "name": "soup"} | | 11 | [] | {"id": 5, "name": "guogege"} | | 12 | [1, 2, 3] | {"id": 4, "name": "guogege"} | +----+----------------+------------------------------+3 rows in set (0.00 sec) mysql> UPDATE testproject SET student = json_set(student, '$.name', 'small', '$.age', 22) WHERE student->'$.id'= 1; Query OK, 1 row affected (0.01 sec) Rows matched: 1 Changed: 1 Warnings: 0 mysql> select * from testproject; +----+----------------+---------------------------------------+| id | skill | student | +----+----------------+---------------------------------------+| 10 | ["js", "java"] | {"id": 1, "age": 22, "name": "small"} | | 11 | [] | {"id": 5, "name": "guogege"} | | 12 | [1, 2, 3] | {"id": 4, "name": "guogege"} | +----+----------------+---------------------------------------+3 rows in set (0.00 sec)
json_insert:
mysql> select * from testproject; +----+----------------+---------------------------------------+ | id | skill | student | +----+----------------+---------------------------------------+ | 10 | ["js", "java"] | {"id": 1, "age": 22, "name": "small"} | | 11 | [] | {"id": 5, "name": "guogege"} | | 12 | [1, 2, 3] | {"id": 4, "name": "guogege"} | +----+----------------+---------------------------------------+ 3 rows in set (0.00 sec) mysql> UPDATE testproject SET student = json_insert(student, '$.name', 'soup', '$.addr', '苏州') WHERE student->'$.id'= 1; Query OK, 1 row affected (0.00 sec) Rows matched: 1 Changed: 1 Warnings: 0 mysql> select * from testproject; +----+----------------+---------------------------------------------------------+ | id | skill | student | +----+----------------+---------------------------------------------------------+ | 10 | ["js", "java"] | {"id": 1, "age": 22, "addr": "苏州", "name": "small"} | | 11 | [] | {"id": 5, "name": "guogege"} | | 12 | [1, 2, 3] | {"id": 4, "name": "guogege"} | +----+----------------+---------------------------------------------------------+ 3 rows in set (0.00 sec)
json_remove() :
mysql> select * from testproject; +----+----------------+---------------------------------------------------------+| id | skill | student | +----+----------------+---------------------------------------------------------+| 10 | ["js", "java"] | {"id": 1, "age": 22, "addr": "苏州", "name": "small"} | | 11 | [] | {"id": 5, "name": "guogege"} | | 12 | [1, 2, 3] | {"id": 4, "name": "guogege"} | +----+----------------+---------------------------------------------------------+3 rows in set (0.00 sec) mysql> UPDATE testproject SET student = json_remove(student, '$.name', '$.age') WHERE student->'$.id' = 1; Query OK, 1 row affected (0.01 sec) Rows matched: 1 Changed: 1 Warnings: 0 mysql> select * from testproject; +----+----------------+------------------------------+| id | skill | student | +----+----------------+------------------------------+| 10 | ["js", "java"] | {"id": 1, "addr": "苏州"} | | 11 | [] | {"id": 5, "name": "guogege"} | | 12 | [1, 2, 3] | {"id": 4, "name": "guogege"} | +----+----------------+------------------------------+3 rows in set (0.00 sec)
可以看到name和age就被移除了。
以上只列出了部分函数的说明,mysql官方提供的函数列表如下:
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作者:我的小碗汤
链接:https://www.jianshu.com/p/b10c9f019d1c