mysql支持原生json使用說明
正文
MySQL在5.7.8開始對json原生支持，本文將對MySQL中json類型的用法簡單說明，但願對你有用。php
CREATE TABLE testproject (
`id` int(10) unsigned NOT NULL AUTO_INCREMENT,
`skill` JSON NOT NULL,
`student` JSON NOT NULL,
PRIMARY KEY (`id`)
);複製代碼
查看錶結構：html
這樣JSON的字段就被建立好了前端
注：JSON類型不能有默認值。vue
插入JSON
插入 json 格式的字符串，能夠是對象的形式，也能夠是數組的形式，java
INSERT INTO `testproject` (student, skill) VALUES ('{"id": 1, "name": "ggjg"}', '["java", "go", "vue"]');
INSERT INTO `testproject` (student, skill) VALUES ('{"id": 5, "name": "guogege"}', '[]');複製代碼
插入json時，數據庫會對json作校驗，不符合json規範就會報錯。python
查詢JSON：
查詢 json 中的數據用 column->path 的形式，其中對象類型 path 這樣表示 $.path, 而數組類型則是 $[index]mysql
查詢testproject表student字段中json對象id爲1的記錄：面試
SELECT * FROM testproject WHERE student->'$.id'= 1;複製代碼
查詢testproject表student字段中json對象id爲1或者5的記錄：spring
SELECT * FROM testproject WHERE student->'$.id' in (1,5);
SELECT * FROM testproject WHERE student->'$.id' = 1 or student->'$.id' = 5;複製代碼
也能夠用函數json_extract：sql
column->path方法有限制，數據源必須是表字段，不然就報錯：
如下這樣查詢，查出來student->'$.name'包含雙引號：
SELECT id, student->'$.id', student->'$.name', skill->'$[0]', skill->'$[2]' FROM testproject;複製代碼
這不是咱們想要的，能夠用 JSONUNQUOTE 函數將雙引號去掉，從 MySQL 5.7.13 起也能夠經過這個操做符 ->> 這個和 JSONUNQUOTE 是等價的。
由於 JSON 不一樣於字符串，因此若是用字符串和 JSON 字段比較，是不會相等的：
mysql> SELECT * FROM testproject WHERE student = '{"id": 1, "name": "ggjg"}';
Empty set (0.00 sec)複製代碼
此時能夠經過 CAST 將字符串轉成 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)複製代碼
要特別注意的是，JSON 中的元素搜索是嚴格區分變量類型的，好比說整型和字符串是嚴格區分的：
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)複製代碼
能夠看到搜索字符串 1 和整型 1 的結果是不同的。
除了用以上 column->path 的形式搜索，還能夠用JSONCONTAINS 函數，但和 column->path 的形式有點相反的是，JSONCONTAINS 第二個參數是不接受整數的，不管 json 元素是整型仍是字符串，不然會出現這個錯誤：
mysql> SELECT * FROM testproject WHERE JSON_CONTAINS(student, 1, '$.id');
ERROR 3146 (22032): Invalid data type for JSON data in argument 2 to function json_contains; a JSON string or JSON type is required.
mysql>複製代碼
這裏必需要使用字符串：
mysql> SELECT * FROM testproject WHERE JSON_CONTAINS(student, '1', '$.id');
+----+-----------------------+---------------------------+
| id | skill | student |
+----+-----------------------+---------------------------+
| 10 | ["java", "go", "vue"] | {"id": 1, "name": "ggjg"} |
+----+-----------------------+---------------------------+
1 row in set (0.00 sec)複製代碼
對於數組類型的 JSON 的查詢，好比說 skill 中包含有 3 的數據，一樣要用 JSON_CONTAINS 函數，一樣第二個參數也須要是字符串：
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)複製代碼
更新數據
MySQL 並不支持 column->path 的形式進行更新操做。
若是是整個 json 更新的話，和插入時相似的：
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)複製代碼
jsonarrayappend和jsonarrayinsert函數使用：
jsonarrayappend是在json後面追加；
jsonarrayinsert是在指定下標插入。
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>複製代碼
jsonreplace、jsonset、jsoninsert和jsonremove函數用法：
json_replace：只替換已經存在的舊值，不存在則忽略；
json_set：替換舊值，並插入不存在的新值；
json_insert：插入新值，但不替換已經存在的舊值；
json_remove() 刪除元素。
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)複製代碼
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->'$.id'= 1;
Query OK, 1 row affected (0.01 sec)
Rows matched: 1 Changed: 1 Warnings: 0
mysql> select * from testproject;
+----+----------------+---------------------------------------+
| id | skill | student |
+----+----------------+---------------------------------------+
| 10 | ["js", "java"] | {"id": 1, "age": 22, "name": "small"} |
| 11 | [] | {"id": 5, "name": "guogege"} |
| 12 | [1, 2, 3] | {"id": 4, "name": "guogege"} |
+----+----------------+---------------------------------------+
3 rows in set (0.00 sec)複製代碼
json_insert：
mysql> select * from testproject;
+----+----------------+---------------------------------------+
| id | skill | student |
+----+----------------+---------------------------------------+
| 10 | ["js", "java"] | {"id": 1, "age": 22, "name": "small"} |
| 11 | [] | {"id": 5, "name": "guogege"} |
| 12 | [1, 2, 3] | {"id": 4, "name": "guogege"} |
+----+----------------+---------------------------------------+
3 rows in set (0.00 sec)
mysql> UPDATE testproject SET student = json_insert(student, '$.name', 'soup', '$.addr', '蘇州') WHERE student->'$.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": "蘇州", "name": "small"} |
| 11 | [] | {"id": 5, "name": "guogege"} |
| 12 | [1, 2, 3] | {"id": 4, "name": "guogege"} |
+----+----------------+---------------------------------------------------------+
3 rows in set (0.00 sec)複製代碼
json_remove() :
mysql> select * from testproject;
+----+----------------+---------------------------------------------------------+
| id | skill | student |
+----+----------------+---------------------------------------------------------+
| 10 | ["js", "java"] | {"id": 1, "age": 22, "addr": "蘇州", "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": "蘇州"} |
| 11 | [] | {"id": 5, "name": "guogege"} |
| 12 | [1, 2, 3] | {"id": 4, "name": "guogege"} |
+----+----------------+------------------------------+
3 rows in set (0.00 sec)複製代碼
能夠看到name和age就被移除了。
以上只列出了部分函數的說明，mysql官方提供的函數列表以下：
更多用法請查看官方文檔：
https://dev.mysql.com/doc/refman/5.7/en/json-function-reference.html
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