從 MySQL 5.7.8 開始,MySQL 支持原生的 JSON 數據類型。
創建 JSON
類似 varchar,設置 JSON 主要將字段的 type 是 json, 不能設置長度,可以是 NULL 但不能有默認值。
mysql> CREATE TABLE lnmp (
`id` int(10) unsigned NOT NULL AUTO_INCREMENT,
`category` JSON,
`tags` JSON,
PRIMARY KEY (`id`)
);
mysql> DESC lnmp;
+----------+------------------+------+-----+---------+----------------+
| Field | Type | Null | Key | Default | Extra |
+----------+------------------+------+-----+---------+----------------+
| id | int(10) unsigned | NO | PRI | NULL | auto_increment |
| category | json | YES | | NULL | |
| tags | json | YES | | NULL | |
+----------+------------------+------+-----+---------+----------------+
3 rows in set (0.00 sec)
這樣 JSON 的字段就創建好了。
插入 JSON
就是插入 json 格式的字符串,可以是對象的形式,也可以是數組的形式
mysql> INSERT INTO `lnmp` (category, tags) VALUES ('{"id": 1, "name": "lnmp.cn"}', '[1, 2, 3]');
Query OK, 1 row affected (0.01 sec)
MySQL 也有專門的函數 JSON_OBJECT,JSON_ARRAY 生成 json 格式的數據
mysql> INSERT INTO `lnmp` (category, tags) VALUES (JSON_OBJECT("id", 2, "name", "php.net"), JSON_ARRAY(1, 3, 5));
Query OK, 1 row affected (0.00 sec)
查看插入的數據
mysql> SELECT * FROM lnmp;
+----+------------------------------+-----------+
| id | category | tags |
+----+------------------------------+-----------+
| 1 | {"id": 1, "name": "lnmp.cn"} | [1, 2, 3] |
| 2 | {"id": 2, "name": "php.net"} | [1, 3, 5] |
+----+------------------------------+-----------+
2 rows in set (0.00 sec)
更多生成 JSON 值的函數請參考: http://dev.mysql.com/doc/refman/5.7/en/json-creation-functions.html
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 $[index]
mysql> SELECT id, category->'$.id', category->'$.name', tags->'$[0]', tags->'$[2]' FROM lnmp;
+----+------------------+--------------------+--------------+--------------+
| id | category->'$.id' | category->'$.name' | tags->'$[0]' | tags->'$[2]' |
+----+------------------+--------------------+--------------+--------------+
| 1 | 1 | "lnmp.cn" | 1 | 3 |
| 2 | 2 | "php.net" | 1 | 5 |
+----+------------------+--------------------+--------------+--------------+
2 rows in set (0.00 sec)
可以看到對應字符串類型的 category->'$.name' 中還包含着雙引號,這其實並不是想要的結果,可以用 JSON_UNQUOTE 函數將雙引號去掉,從 MySQL 5.7.13 起也可以通過這個操作符 ->> 這個和 JSON_UNQUOTE 是等價的
mysql> SELECT id, category->'$.name', JSON_UNQUOTE(category->'$.name'), category->>'$.name' FROM lnmp;
+----+--------------------+----------------------------------+---------------------+
| id | category->'$.name' | JSON_UNQUOTE(category->'$.name') | category->>'$.name' |
+----+--------------------+----------------------------------+---------------------+
| 1 | "lnmp.cn" | lnmp.cn | lnmp.cn |
| 2 | "php.net" | php.net | php.net |
+----+--------------------+----------------------------------+---------------------+
2 rows in set (0.00 sec)
下面說下 JSON 作爲條件進行搜索。因爲 JSON 不同於字符串,所以如果用字符串和 JSON 字段比較,是不會相等的
mysql> SELECT * FROM lnmp WHERE category = '{"id": 1, "name": "lnmp.cn"}';
Empty set (0.00 sec)
這時可以通過 CAST 將字符串轉成 JSON 的形式
mysql> SELECT * FROM lnmp WHERE category = CAST('{"id": 1, "name": "lnmp.cn"}' as JSON);
+----+------------------------------+-----------+
| id | category | tags |
+----+------------------------------+-----------+
| 1 | {"id": 1, "name": "lnmp.cn"} | [1, 2, 3] |
+----+------------------------------+-----------+
1 row in set (0.00 sec)
通過 JSON 中的元素進行查詢, 對象型的查詢同樣可以通過 column->path
mysql> SELECT * FROM lnmp WHERE category->'$.name' = 'lnmp.cn';
+----+------------------------------+-----------+
| id | category | tags |
+----+------------------------------+-----------+
| 1 | {"id": 1, "name": "lnmp.cn"} | [1, 2, 3] |
+----+------------------------------+-----------+
1 row in set (0.00 sec)
上面有提到 column->path 形式從 select 中查詢出來的字符串是包含雙引號的,但作爲條件這裏其實沒什麼影響,-> 和 ->> 結果是一樣的
mysql> SELECT * FROM lnmp WHERE category->>'$.name' = 'lnmp.cn';
+----+------------------------------+-----------+
| id | category | tags |
+----+------------------------------+-----------+
| 1 | {"id": 1, "name": "lnmp.cn"} | [1, 2, 3] |
+----+------------------------------+-----------+
1 row in set (0.00 sec)
要特別注意的是,JSON 中的元素搜索是嚴格區分變量類型的,比如說整型和字符串是嚴格區分的
mysql> SELECT * FROM lnmp WHERE category->'$.id' = '1';
Empty set (0.00 sec)
mysql> SELECT * FROM lnmp WHERE category->'$.id' = 1;
+----+------------------------------+-----------+
| id | category | tags |
+----+------------------------------+-----------+
| 1 | {"id": 1, "name": "lnmp.cn"} | [1, 2, 3] |
+----+------------------------------+-----------+
1 row in set (0.00 sec)
可以看到搜索字符串 1 和整型 1 的結果是不一樣的。
除了用 column->path 的形式搜索,還可以用JSON_CONTAINS 函數,但和 column->path 的形式有點相反的是,JSON_CONTAINS 第二個參數是不接受整數的,無論 json 元素是整型還是字符串,否則會出現這個錯誤
mysql> SELECT * FROM lnmp WHERE JSON_CONTAINS(category, 1, '$.id');
ERROR 3146 (22032): Invalid data type for JSON data in argument 2 to function json_contains; a JSON string or JSON type is required.
這裏必須是要字符串 1
mysql> SELECT * FROM lnmp WHERE JSON_CONTAINS(category, '1', '$.id');
+----+------------------------------+-----------+
| id | category | tags |
+----+------------------------------+-----------+
| 1 | {"id": 1, "name": "lnmp.cn"} | [1, 2, 3] |
+----+------------------------------+-----------+
1 row in set (0.01 sec)
對於數組類型的 JSON 的查詢,比如說 tags 中包含有 2 的數據,同樣要用 JSON_CONTAINS 函數,同樣第二個參數也需要是字符串
mysql> SELECT * FROM lnmp WHERE JSON_CONTAINS(tags, '2');
+----+------------------------------+-----------+
| id | category | tags |
+----+------------------------------+-----------+
| 1 | {"id": 1, "name": "lnmp.cn"} | [1, 2, 3] |
+----+------------------------------+-----------+
1 row in set (0.00 sec)
更多搜索 JSON 值的函數請參考:http://dev.mysql.com/doc/refman/5.7/en/json-search-functions.html
更新 JSON
如果是整個 json 更新的話,和插入時類似的。
mysql> UPDATE lnmp SET tags = '[1, 3, 4]' WHERE id = 1;
Query OK, 1 row affected (0.00 sec)
Rows matched: 1 Changed: 1 Warnings: 0
mysql> SELECT * FROM lnmp;
+----+------------------------------+-----------+
| id | category | tags |
+----+------------------------------+-----------+
| 1 | {"id": 1, "name": "lnmp.cn"} | [1, 3, 4] |
| 2 | {"id": 2, "name": "php.net"} | [1, 3, 5] |
+----+------------------------------+-----------+
2 rows in set (0.00 sec)
但如果要更新 JSON 下的元素,MySQL 並不支持 column->path 的形式
mysql> UPDATE lnmp SET category->'$.name' = 'lnmp', tags->'$[0]' = 2 WHERE id = 1;
ERROR 1064 (42000): You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '->'$.name' = 'lnmp', tags->'$[0]' = 2 WHERE id = 1' at line 1
則可能要用到以下幾個函數
JSON_INSERT() 插入新值,但不會覆蓋已經存在的值
mysql> UPDATE lnmp SET category = JSON_INSERT(category, '$.name', 'lnmp', '$.url', 'www.lnmp.cn') WHERE id = 1;
Query OK, 1 row affected (0.00 sec)
Rows matched: 1 Changed: 1 Warnings: 0
mysql> SELECT * FROM lnmp; +----+----------------------------------------------------+-----------+
| id | category | tags |
+----+----------------------------------------------------+-----------+
| 1 | {"id": 1, "url": "www.lnmp.cn", "name": "lnmp.cn"} | [1, 3, 4] |
| 2 | {"id": 2, "name": "php.net"} | [1, 3, 5] |
+----+----------------------------------------------------+-----------+
2 rows in set (0.00 sec)
可以看到 name 沒有被修改,但新元素 url 已經添加進去
JSON_SET() 插入新值,並覆蓋已經存在的值
mysql> UPDATE lnmp SET category = JSON_SET(category, '$.host', 'www.lnmp.cn', '$.url', 'http://www.lnmp.cn') WHERE id = 1;
Query OK, 1 row affected (0.00 sec)
Rows matched: 1 Changed: 1 Warnings: 0
mysql> SELECT * FROM lnmp; +----+----------------------------------------------------------------------------------+-----------+
| id | category | tags |
+----+----------------------------------------------------------------------------------+-----------+
| 1 | {"id": 1, "url": "http://www.lnmp.cn", "host": "www.lnmp.cn", "name": "lnmp.cn"} | [1, 3, 4] |
| 2 | {"id": 2, "name": "php.net"} | [1, 3, 5] |
+----+----------------------------------------------------------------------------------+-----------+
2 rows in set (0.00 sec)
可以看到 host 已經插入,url 已經被修改
JSON_REPLACE() 只替換存在的值
mysql> UPDATE lnmp SET category = JSON_REPLACE(category, '$.name', 'php', '$.url', 'http://www.php.net') WHERE id = 2;
Query OK, 1 row affected (0.01 sec)
Rows matched: 1 Changed: 1 Warnings: 0
mysql> SELECT * FROM lnmp;
+----+----------------------------------------------------------------------------------+-----------+
| id | category | tags |
+----+----------------------------------------------------------------------------------+-----------+
| 1 | {"id": 1, "url": "http://www.lnmp.cn", "host": "www.lnmp.cn", "name": "lnmp.cn"} | [1, 3, 4] |
| 2 | {"id": 2, "name": "php"} | [1, 3, 5] |
+----+----------------------------------------------------------------------------------+-----------+
2 rows in set (0.00 sec)
可以看到 name 已經被替換,url 不存在被忽略。
JSON_REMOVE() 刪除 JSON 元素
mysql> UPDATE lnmp SET category = JSON_REMOVE(category, '$.url', '$.host') WHERE id = 1;
Query OK, 1 row affected (0.01 sec)
Rows matched: 1 Changed: 1 Warnings: 0
mysql> SELECT * FROM lnmp;
+----+------------------------------+-----------+
| id | category | tags |
+----+------------------------------+-----------+
| 1 | {"id": 1, "name": "lnmp.cn"} | [1, 3, 4] |
| 2 | {"id": 2, "name": "php"} | [1, 3, 5] |
+----+------------------------------+-----------+
2 rows in set (0.00 sec)
更多函數請參考:http://dev.mysql.com/doc/refman/5.7/en/json-modification-functions.html
MySQL JSON 在 PHP 中的表現
雖然在 MySQL 是個JSON 類型,但實際在 PHP 應用中返回的是 JSON 格式的字符串
array(2) { [0]=> array(3) { ["id"]=> string(1) "1" ["category"]=> string(28) "{"id": 1, "name": "lnmp.cn"}" ["tags"]=> string(9) "[1, 3, 4]" } [1]=> array(3) { ["id"]=> string(1) "2" ["category"]=> string(24) "{"id": 2, "name": "php"}" ["tags"]=> string(9) "[1, 3, 5]" } }原文鏈接