MySQL5.7中新增的JSON类型的使用方法
创建表json_test:
CREATE TABLE json_test(id INT(11) AUTO_INCREMENT PRIMARY KEY,person_desc JSON)ENGINE INNODB;
插入一条记录：
INSERT INTO json_test(person_desc) VALUES ('{
"programmers": [{
"firstName": "Brett",
"lastName": "McLaughlin",
"email": "aaaa"
}, {
"firstName": "Jason",
"lastName": "Hunter",
"email": "bbbb"
}, {
"firstName": "Elliotte",
"lastName": "Harold",
"email": "cccc"
}],
"authors": [{
"firstName": "Isaac",
"lastName": "Asimov",
"genre": "sciencefiction"
}, {
"firstName": "Tad",
"lastName": "Williams",
"genre": "fantasy"
}, {
"firstName": "Frank",
"lastName": "Peretti",
"genre": "christianfiction"
}],
"musicians": [{
"firstName": "Eric",
"lastName": "Clapton",
"instrument": "guitar"
}, {
"firstName": "Sergei",
"lastName": "Rachmaninoff",
"instrument": "piano"
}]
}');
查看插入的这行JSON数据有哪些KEY：
mysql> SELECT id,json_keys(person_desc) as "keys" FROM json_test\G *************************** 1. row *************************** id: 1 keys: ["authors", "musicians", "programmers"] 1 row in set (0.00 sec)
可以看到里面有三个KEY，分别为authors，musicians，programmers。那现在找一个KEY把对应的值拿出来：
mysql> SELECT json_extract(AUTHORS,'$.lastName[0]') AS 'name', AUTHORS FROM
-> (
-> SELECT id,json_extract(person_desc,'$.authors[0][0]') AS "authors" FROM json_test
-> UNION ALL
-> SELECT id,json_extract(person_desc,'$.authors[1][0]') AS "authors" FROM json_test
-> UNION ALL
-> SELECT id,json_extract(person_desc,'$.authors[2][0]') AS "authors" FROM json_test
-> ) AS T1
-> ORDER BY NAME DESC\G
*************************** 1. row ***************************
name: "Williams"
AUTHORS: {"genre": "fantasy", "lastName": "Williams", "firstName": "Tad"}
*************************** 2. row ***************************
name: "Peretti"
AUTHORS: {"genre": "christianfiction", "lastName": "Peretti", "firstName": "Frank"}
*************************** 3. row ***************************
name: "Asimov"
AUTHORS: {"genre": "sciencefiction", "lastName": "Asimov", "firstName": "Isaac"}
3 rows in set (0.00 sec)
列出详细值：
mysql> SELECT -> json_extract(AUTHORS,'$.firstName[0]') AS "firstname", -> json_extract(AUTHORS,'$.lastName[0]') AS "lastname", -> json_extract(AUTHORS,'$.genre[0]') AS "genre" -> FROM -> ( -> SELECT id,json_extract(person_desc,'$.authors[0]') AS "authors" FROM json _test -> ) AS T\G *************************** 1. row *************************** firstname: "Isaac" lastname: "Asimov" genre: "sciencefiction" 1 row in set (0.00 sec)
删掉authors这个KEY对应的所有对象：
mysql> UPDATE json_test SET person_desc = json_remove(person_desc,'$.authors')\G Query OK, 1 row affected (0.01 sec) Rows matched: 1 Changed: 1 Warnings: 0
查找对应的KEY，发现已经被删除掉：
mysql> SELECT json_contains_path(person_desc,'all','$.authors') as authors_exist s FROM json_test\G *************************** 1. row *************************** authors_exists: 0 1 row in set (0.00 sec)
