Basic JSON operations of MySQL 5.7

MySQL5.7 Of JSON Basic operation

1、 Build table

When creating a new table, the field type can be directly set to json type , For example, we create a table ：

create table `test_user`
(
    `id`   int primary key auto_increment,
    `name` varchar(50) not null,
    `info` json
);

json The type field can be NULL

2、 Insert

（1） Build directly with strings json object

insert into test_user(`name`, `info`)
values ('xiaoming', '{ "sex": 1, "age": 18, "nick_name": " Xiaomeng " }');

json A field of type must be a valid json character string

（2） have access to JSON_OBJECT() The function structure json object

insert into test_user(`name`, `info`)
values ('xiaohua', json_object("sex", 0, "age", 17));

（3） Use JSON_ARRAY() The function structure json Array

insert into test_user(`name`, `info`)
values ('xiaozhang', json_object("sex", 1, "age", 19, "tag", json_array(3, 5, 90)));

see test_user Table data ：

mysql> select * from test_user;
+----+-----------+----------------------------------------------+
| id | name      | info                                         |
+----+-----------+----------------------------------------------+
|  1 | xiaoming  | {
   "age": 18, "sex": 1, "nick_name": " Xiaomeng "}   |
|  2 | xiaohua   | {
   "age": 17, "sex": 0}                        |
|  3 | xiaozhang | {
   "age": 19, "sex": 1, "tag": [3, 5, 90]}     |
+----+-----------+----------------------------------------------+
3 rows in set (0.00 sec)

3、 Inquire about

（1） Inquire about json attribute

expression ： The object is json Column ->'$. key ', The array is json Column ->'$. key [index]'

mysql> select name, info -> '$.nick_name' as nick_name, info -> '$.sex' as sex, info -> '$.tag[0]' as 1st_tag from test_user;
+-----------+-----------+------+---------+
| name      | nick_name | sex  | 1st_tag |
+-----------+-----------+------+---------+
| xiaoming  | " Xiaomeng "    | 1    | NULL    |
| xiaohua   | NULL      | 0    | NULL    |
| xiaozhang | NULL      | 1    | 3       |
+-----------+-----------+------+---------+
3 rows in set (0.00 sec)

Equivalent to ： The object is JSON_EXTRACT(json Column , '$. key '), The array is JSON_EXTRACT(json Column , '$. key [index]')

mysql> select name, JSON_EXTRACT(info, '$.nick_name') as nick_name, JSON_EXTRACT(info, '$.sex') as sex, JSON_EXTRACT(info, '$.tag[0]') as 1st_tag from test_user;
+-----------+-----------+------+---------+
| name      | nick_name | sex  | 1st_tag |
+-----------+-----------+------+---------+
| xiaoming  | " Xiaomeng "    | 1    | NULL    |
| xiaohua   | NULL      | 0    | NULL    |
| xiaozhang | NULL      | 1    | 3       |
+-----------+-----------+------+---------+
3 rows in set (0.00 sec)

But when you see it " Xiaomeng " It's in double quotation marks , This is not what we want , It can be used JSON_UNQUOTE Function to remove double quotes

mysql> select name, JSON_UNQUOTE(info -> '$.nick_name') as nick_name from test_user where name = 'xiaoming';
+----------+-----------+
| name     | nick_name |
+----------+-----------+
| xiaoming |  Xiaomeng       |
+----------+-----------+
1 row in set (0.00 sec)

You can also use the operator directly ->>

mysql> select name, info ->> '$.nick_name' as nick_name from test_user where name = 'xiaoming';
+----------+-----------+
| name     | nick_name |
+----------+-----------+
| xiaoming |  Xiaomeng       |
+----------+-----------+
1 row in set (0.00 sec)

（2）json Attribute as query criteria

mysql> select name, info ->> '$.nick_name' as nick_name from test_user where info -> '$.nick_name' = ' Xiaomeng ';
+----------+-----------+
| name     | nick_name |
+----------+-----------+
| xiaoming |  Xiaomeng       |
+----------+-----------+
1 row in set (0.00 sec)

（3） adopt Virtual column Yes JSON Quick query of the specified properties of type .

Create virtual columns :

mysql> alter table `test_user` add `nick_name` varchar(50) generated always as (info ->> '$.nick_name') virtual;

Note the operator ->> Remove double quotes

Delete virtual column

mysql> alter table `test_user` drop `nick_name`;

When used, it is the same as the ordinary type of column query :

mysql> select name, nick_name from test_user where nick_name = ' Xiaomeng ';
+----------+-----------+
| name     | nick_name |
+----------+-----------+
| xiaoming |  Xiaomeng       |
+----------+-----------+
1 row in set (0.00 sec)

4、 to update

（1） Use JSON_INSERT() Insert new value , But it will not overwrite the existing value

Before updating

mysql> select * from test_user where id = 2;
+----+---------+-----------------------+-----------+
| id | name    | info                  | nick_name |
+----+---------+-----------------------+-----------+
|  2 | xiaohua | {
   "age": 17, "sex": 0} | NULL      |
+----+---------+-----------------------+-----------+
1 row in set (0.00 sec)

to update

mysql> update test_user set info = json_insert(info, '$.sex', 1, '$.nick_name', ' floret ') where id = 2;
Query OK, 1 row affected (0.01 sec)
Rows matched: 1  Changed: 1  Warnings: 0

After the update

mysql> select * from test_user where id = 2;
+----+---------+----------------------------------------------+-----------+
| id | name    | info                                         | nick_name |
+----+---------+----------------------------------------------+-----------+
|  2 | xiaohua | {
   "age": 17, "sex": 0, "nick_name": " floret "}   |  floret       |
+----+---------+----------------------------------------------+-----------+
1 row in set (0.00 sec)

（2） Use JSON_SET() Insert new value , And overwrite the existing value

Before updating

mysql> select * from test_user where id = 3;
+----+-----------+------------------------------------------+-----------+
| id | name      | info                                     | nick_name |
+----+-----------+------------------------------------------+-----------+
|  3 | xiaozhang | {
   "age": 19, "sex": 1, "tag": [3, 5, 90]} | NULL      |
+----+-----------+------------------------------------------+-----------+
1 row in set (0.00 sec)

to update

mysql> update test_user set info = json_set(info, '$.age', 20, '$.sex', 0, '$.nick_name', ' Xiao Zhang ') where id = 3;
Query OK, 1 row affected (0.03 sec)
Rows matched: 1  Changed: 1  Warnings: 0

After the update

mysql> select * from test_user where id = 3;
+----+-----------+-----------------------------------------------------------------+-----------+
| id | name      | info                                                            | nick_name |
+----+-----------+-----------------------------------------------------------------+-----------+
|  3 | xiaozhang | {
   "age": 20, "sex": 0, "tag": [3, 5, 90], "nick_name": " Xiao Zhang "}   |  Xiao Zhang       |
+----+-----------+-----------------------------------------------------------------+-----------+
1 row in set (0.00 sec)

（3） Use JSON_REPLACE() Replace only existing values

Before updating

mysql> select * from test_user where id = 2;
+----+---------+----------------------------------------------+-----------+
| id | name    | info                                         | nick_name |
+----+---------+----------------------------------------------+-----------+
|  2 | xiaohua | {
   "age": 17, "sex": 0, "nick_name": " floret "}   |  floret       |
+----+---------+----------------------------------------------+-----------+
1 row in set (0.00 sec)

to update

mysql> update test_user set info = json_replace(info, '$.sex', 1, '$.tag', '[1,2,3]') where id = 2;
Query OK, 1 row affected (0.02 sec)
Rows matched: 1  Changed: 1  Warnings: 0

After the update

mysql> select * from test_user where id = 2;
+----+---------+----------------------------------------------+-----------+
| id | name    | info                                         | nick_name |
+----+---------+----------------------------------------------+-----------+
|  2 | xiaohua | {
   "age": 17, "sex": 1, "nick_name": " floret "}   |  floret       |
+----+---------+----------------------------------------------+-----------+
1 row in set (0.00 sec)

You can see tag Not updated

（4） Use JSON_REMOVE() Delete JSON Elements

Before updating

mysql> select * from test_user where id = 1;
+----+----------+----------------------------------------------+-----------+
| id | name     | info                                         | nick_name |
+----+----------+----------------------------------------------+-----------+
|  1 | xiaoming | {
   "age": 18, "sex": 1, "nick_name": " Xiaomeng "}   |  Xiaomeng       |
+----+----------+----------------------------------------------+-----------+
1 row in set (0.00 sec)

to update

mysql> update test_user set info = json_remove(info, '$.sex', '$.tag') where id = 1;
Query OK, 1 row affected (0.05 sec)
Rows matched: 1  Changed: 1  Warnings: 0

After the update

mysql> select * from test_user where id = 1;
+----+----------+------------------------------------+-----------+
| id | name     | info                               | nick_name |
+----+----------+------------------------------------+-----------+
|  1 | xiaoming | {
   "age": 18, "nick_name": " Xiaomeng "}   |  Xiaomeng       |
+----+----------+------------------------------------+-----------+
1 row in set (0.00 sec)