目录
- 1. JSON 介绍
- 官方文档 (JSON 类型 )
- 2. JSON 格式示例
- --
- -- 摘自 维基百科
- --
- {
- 3. JSON VS BLOB
- • JSON
- ◦ JSON 数据可以做有效性检查 ;
- ◦ JSON 使得查询性能提升 ;
- ◦ JSON 支持部分属性索引，通过虚拟列的功能可以对 JSON 中的部分数据进行索引 ;
- • BLOB
- ◦ BLOB 类型无法在数据库层做约束性检查 ;
- ◦ BLOB 进行查询，需要遍历所有字符串 ;
- ◦ BLOB 做只能做指定长度的索引 ;
- 5.7 之前，只能把 JSON 当作 BLOB 进行存储。数据库层面无法对 JSON 数据做一些操作，只能由应用程序处理。
- 4.结构化和非结构化
- • 结构化
- ◦ 二维表结构（行和列）
- ◦ 使用 SQL 语句进行操作
- • 非结构化
- --
- 5. JSON 操作示例
- 5.1 JSON 入门
- --
- 5.2 JSON 常用函数介绍
- --
- --
- --
- --
- --
- 官方文档 (JSON 函数 )
- 5.3 JSON 创建索引
- 官方文档 –JSON 创建索引
- • 新建表时创建 JSON 索引
- • 修改已存在的表创建 JSON 索引
- --
- 二. 附录
- --
- -- 老师演示 JSON 的SQL
- --
MySQL--JSON
MySQL 学习
MySQL 学习笔记（ Day009 ：JSON ）
一. MySQL JSON 类型
- JSON 介绍
- JSON 格式示例
- JSON VS BLOB
4.结构化和非结构化 - JSON 操作示例
5.1 JSON 入门
5.2 JSON 常用函数介绍
5.3 JSON 创建索引
二. 附录
一. MySQL JSON类型
1. JSON 介绍
- JSON （Java Script Object Notation ）是一种轻量级的数据交换语言，并且是独立于语言的文本格式。
- 一些 NoSQL 数据库 选择 JSON 作为其数据存储格式，比如： MongoDB 、CouchDB 等。
- MySQL 5.7.x 开始支持 JSON 数据类型。
官方文档 (JSON 类型 )
2. JSON 格式示例
--
-- 摘自 维基百科
--
{
"firstName": "John", -- Key : Value 格式
"lastName": "Smith",
"sex": "male",
"age": 25,
"address": -- Key : Value ; 其中 Value 也是一个 Key-Value 的结构
{
"streetAddress": "21 2nd Street",
"city": "New York",
"state": "NY",
"postalCode": "10021"
},
"phoneNumber":
[
{
"type": "home",
"number": "212 555-1234"
},
{
"type": "fax",
"number": "646 555-4567"
}
]
}
3. JSON VS BLOB
• JSON
◦ JSON 数据可以做有效性检查 ;
◦ JSON 使得查询性能提升 ;
◦ JSON 支持部分属性索引，通过虚拟列的功能可以对 JSON 中的部分数据进行索引 ;
• BLOB
◦ BLOB 类型无法在数据库层做约束性检查 ;
◦ BLOB 进行查询，需要遍历所有字符串 ;
◦ BLOB 做只能做指定长度的索引 ;
5.7 之前，只能把 JSON 当作 BLOB 进行存储。数据库层面无法对 JSON 数据做一些操作，只能由应用程序处理。
4.结构化和非结构化
• 结构化
◦ 二维表结构（行和列）
◦ 使用 SQL 语句进行操作
• 非结构化
◦ 使用 Key-Value 格式定义数据，无结构定义
◦ Value 可以嵌套 Key-Value 格式的数据
◦ 使用 JSON 进行实现
--
-- SQL 创建 User 表
--
create table user (
id bigint not null auto_increment,
user_name varchar ( 10 ),
age int ,
primary key (id)
);
# JSON 定义的 User 表
#
db.user.insert({
user_name: "tom" ,
age: 30
})
db.createCollection( "user" )
5. JSON 操作示例
5.1 JSON 入门
--
-- 创建带 json 字段的表
--
mysql> create table user (
-> uid int auto_increment,
-> data json,
-> primary key (uid)
-> );
Query OK, 0 rows affected (0.11 sec)
--
-- 插入 json 数据
--
mysql> insert into user values (
-> null , -- 自增长数据，可以插入 null
-> '{
' > "name" :"tom" ,
'> "age":18,
' > "address" :"SZ"
'> }'
-> );
Query OK, 1 row affected (0.03 sec)
mysql> insert into user values (
-> null ,
-> '{
' > "name" :"jim" ,
'> "age":28,
' > "mail" :"jim@163.com"
'> }'
-> );
Query OK, 1 row affected (0.02 sec)
mysql> insert into user values ( null , "can you insert it?" ); -- 无法插入，因为是 JSON 类型
ERROR 3140 (22032): Invalid JSON text: "Invalid value." at position 0 in value (or column) can you insert it?. -- 这短话有单引号，但是渲染有问题，所以这里去掉了
mysql> select * from user ;
+-----+---------------------------------------------------+
| uid | data |
+-----+---------------------------------------------------+
| 1 | {"age": 18, "name": "tom", "address": "SZ"} | -- 这个 json 中有 address 字段
| 2 | {"age": 28, "mail": "jim@163.com", "name": "jim"} | -- 这个 json 中有 mail 字段
+-----+---------------------------------------------------+
2 rows in set ( 0.00 sec)
5.2 JSON 常用函数介绍
--
-- 使用 json_extract 提取数据
-- 原型 : JSON_EXTRACT(json_doc, path[, path] ...)
--
mysql> select json_extract( '[10, 20, [30, 40]]' , '$[1]' );
+--------------------------------------------+
| json_extract('[10, 20, [30, 40]]', '$[1]') |
+--------------------------------------------+
| 20 | -- 从list 中抽取 下标 为 1 的元素（下标从 0 开始）
+--------------------------------------------+
1 row in set ( 0.00 sec)
mysql> select
-> json_extract( data , '$.name' ), -- 提起 name 字段的数据
-> json_extract( data , '$.address' ) -- 提取 address字段的数据
-> from user ;
+------------------------------+---------------------------------+
| json_extract(data, '$.name') | json_extract(data, '$.address') |
+------------------------------+---------------------------------+
| "tom" | "SZ" |
| "jim" | NULL | -- jim 没有 address 字段，填充了 NULL
+------------------------------+---------------------------------+
2 rows in set ( 0.00 sec)
--
-- json_object 将list(K-V 对)封装成 json 格式
-- 原型 : JSON_OBJECT([key, val[, key, val] ...])
--
mysql> select json_object( "name" , "jery" , "email" , "jery@163.com" , "age" , 33 );
+----------------------------------------------------------------+
| json_object("name", "jery", "email", "jery@163.com", "age",33) |
+----------------------------------------------------------------+
| {"age": 33, "name": "jery", "email": "jery@163.com"} | -- 封装成了 K-V 对
+----------------------------------------------------------------+
1 row in set ( 0.00 sec)
mysql> insert into user values (
-> null ,
-> json_object("name" , "jery" , "email", "jery@163.com" , "age" , 33 ) -- 进行封装
-> );
Query OK, 1 row affected (0.03 sec)
mysql> select * from user ;
+-----+------------------------------------------------------+
| uid | data |
+-----+------------------------------------------------------+
| 1 | {"age": 18, "name": "tom", "address": "SZ"} |
| 2 | {"age": 28, "mail": "jim@163.com", "name": "jim"} |
| 4 | {"age": 33, "name": "jery", "email": "jery@163.com"} |
+-----+------------------------------------------------------+
3 rows in set ( 0.00 sec)
--
-- json_insert 插入数据
-- 原型 : JSON_INSERT(json_doc, path, val[, path, val] ...)
--
mysql> set @j = '{ "a": 1, "b": [2, 3]}' ;
Query OK, 0 rows affected (0.00 sec)
mysql> select json_insert(@j, '$.a' , 10 , '$.c' , '[true, false]' );
+----------------------------------------------------+
| json_insert(@j, '$.a', 10, '$.c', '[true, false]') |
+----------------------------------------------------+
| {"a": 1, "b": [2, 3], "c": "[true, false]"} | -- a 还是 =1 ，存在的被忽略，不受影响
+----------------------------------------------------+ -- c 之前不存在，则插入
1 row in set ( 0.00 sec)
mysql> update user set data = json_insert( data , "$.address_2" , "BJ" ) where uid = 1 ; -- 插入 addres_
Query OK, 1 row affected (0.03 sec)
Rows matched: 1 Changed: 1 Warnings: 0
mysql> select * from user ;
+-----+----------------------------------------------------------------+
| uid | data |
+-----+----------------------------------------------------------------+
| 1 | {"age": 18, "name": "tom", "address": "SZ", "address_2": "BJ"} | -- 增加了 addres_2 : "BJ"
| 2 | {"age": 28, "mail": "jim@163.com", "name": "jim"} |
| 4 | {"age": 33, "name": "jery", "email": "jery@163.com"} |
+-----+----------------------------------------------------------------+
3 rows in set ( 0.00 sec)
--
-- json_merge 合并数据并返回。注意：原数据不受影响
-- 原型 : JSON_MERGE(json_doc, json_doc[, json_doc] ...)
--
mysql> select json_merge( '{"name": "x"}' , '{"id": 47}' ); -- 原来有两个 JSON
+-------------------------------------------+
| json_merge('{"name": "x"}', '{"id": 47}') |
+-------------------------------------------+
| {"id": 47, "name": "x"} | -- 合并多个 JSON
+-------------------------------------------+
1 row in set ( 0.00 sec)
mysql> select
-> json_merge(
-> json_extract( data , '$.address' ), -- json 1
-> json_extract( data , '$.address_2' )) -- jons 2
-> from user where uid = 1 ;
+---------------------------------------------------------------------------------+
| json_merge( json_extract(data, '$.address'), json_extract(data, '$.address_2')) |
+---------------------------------------------------------------------------------+
| ["SZ", "BJ"] | -- 合并成一个 json
+---------------------------------------------------------------------------------+
1 row in set ( 0.00 sec)
--
-- json_array_append 追加数据
-- 原型 : JSON_ARRAY_APPEND(json_doc, path, val[, path, val] ...)
-- json_append 在5.7.9 中重命名为 json_array_append
--
mysql> set @j = '["a", ["b", "c"], "d"]' ; -- 下标为 1 的元素中只有 ["b", "c"]
Query OK, 0 rows affected (0.00 sec)
mysql> select json_array_append(@j, '$[1]' , 1 );
+----------------------------------+
| json_array_append(@j, '$[1]', 1) |
+----------------------------------+
| ["a", ["b", "c", 1], "d"] | -- 现在插入了 数字 1
+----------------------------------+
1 row in set ( 0.00 sec)
mysql> update user set data = json_array_append(
-> data ,
-> '$.address' ,
-> json_extract( data , '$.address_2' ))
-> where uid = 1 ;
Query OK, 1 row affected (0.02 sec)
Rows matched: 1 Changed: 1 Warnings: 0
mysql> select * from user ;
+-----+------------------------------------------------------------------------+
| uid | data |
+-----+------------------------------------------------------------------------+
| 1 | {"age": 18, "name": "tom", "address": ["SZ", "BJ"], "address_2": "BJ"} | --address_2 追加到 address
| 2 | {"age": 28, "mail": "jim@163.com", "name": "jim"} |
| 4 | {"age": 33, "name": "jery", "email": "jery@163.com"} |
+-----+------------------------------------------------------------------------+
3 rows in set ( 0.00 sec)
--
-- json_remove 从json 记录中删除数据
-- 原型 : JSON_REMOVE(json_doc, path[, path] ...)
--
mysql> set @j = '["a", ["b", "c"], "d"]' ;
Query OK, 0 rows affected (0.00 sec)
mysql> select json_remove(@j, '$[1]' );
+-------------------------+
| json_remove(@j, '$[1]') |
+-------------------------+
| ["a", "d"] | -- 删除了下标为 1 的元素 ["b", "c"]
+-------------------------+
1 row in set ( 0.00 sec)
mysql> update user set data = json_remove( data , "$.address_2" ) where uid = 1 ;
Query OK, 1 row affected (0.03 sec)
Rows matched: 1 Changed: 1 Warnings: 0
mysql> select * from user ;
+-----+------------------------------------------------------+
| uid | data |
+-----+------------------------------------------------------+
| 1 | {"age": 18, "name": "tom", "address": ["SZ", "BJ"]} | -- address_2 的字段删除了
| 2 | {"age": 28, "mail": "jim@163.com", "name": "jim"} |
| 4 | {"age": 33, "name": "jery", "email": "jery@163.com"} |
+-----+------------------------------------------------------+
3 rows in set ( 0.00 sec)
官方文档 (JSON 函数 )
5.3 JSON 创建索引
JSON 类型数据本身 无法直接 创建索引，需要将需要索引的 JSON 数据 重新 生成虚拟列 (Virtual Columns) 之后，对 该列 进行 索引
官方文档 –JSON 创建索引
• 新建表时创建 JSON 索引
mysql> create table test_inex_1(
-> data json,
-> gen_col varchar ( 10 ) generated always as (json_extract( data , '$.name' )), -- 抽取 data 中的 name ， 生成新的一列，名字为 gen_col
-> index idx (gen_col) -- 将gen_col 作为索引
-> );
Query OK, 0 rows affected (0.13 sec)
mysql> show create table test_index_1 ；
-- -----省略表格线 -----
| test_index_1 | CREATE TABLE `test_index_1` (
`data` json DEFAULT NULL ,
`gen_col` varchar ( 10 ) GENERATED ALWAYS AS (json_extract( data , '$.name' )) VIRTUAL,
KEY `idx` ( `gen_col` )
) ENGINE =InnoDB DEFAULT CHARSET=utf8mb4 |
-- -----省略表格线 -----
1 row in set ( 0.00 sec)
mysql> insert into test_index_1( data ) values ( '{"name":"tom", "age":18, "address":"SH"}');
Query OK, 1 row affected (0.04 sec)
mysql> insert into test_index_1( data ) values ( '{"name":"jim", "age":28, "address":"SZ"}');
Query OK, 1 row affected (0.03 sec)
mysql> select * from test_index_1;
+---------------------------------------------+---------+
| data | gen_col |
+---------------------------------------------+---------+
| {"age": 18, "name": "tom", "address": "SH"} | "tom" |
| {"age": 28, "name": "jim", "address": "SZ"} | "jim" |
+---------------------------------------------+---------+
2 rows in set ( 0.00 sec)
mysql> select json_extract( data ,"$.name" ) as username from test_index_1 where gen_col= "tom" ; -- 如果这样做，为空，原因如下
Empty set ( 0.00 sec)
mysql> select hex ('"' );
+----------+
| hex('"') |
+----------+
| 22 | -- 双引号的 16 进制
+----------+
1 row in set ( 0.00 sec)
mysql> select hex (gen_col) from test_index_1;
+--------------+
| hex(gen_col) |
+--------------+
| 226A696D22 | -- 双引号本身也作为了存储内容
| 22746F6D22 |
+--------------+
2 rows in set ( 0.00 sec)
mysql> select json_extract( data ,"$.name" ) as username from test_index_1 where gen_col= '"tom"' ; -- 使用 '"tome"',用单引号括起来
+----------+
| username |
+----------+
| "tom" | -- 找到了对应的数据
+----------+
1 row in set ( 0.00 sec)
mysql> explain select json_extract( data ,"$.name" ) as username from test_index_1 where gen_col= '"tom"' G
*************************** 1. row ***************************
id: 1
select_type: SIMPLE
table : test_index_
partitions: NULL
type: ref
possible_keys: idx -- 使用了 key idx
key : idx
key_len: 43
ref: const
rows : 1
filtered: 100.
Extra: NULL
1 row in set , 1 warning ( 0.00 sec)
---
--- 建立表的时候去掉双引用
---
mysql> create table test_index_2 (
-> data json,
-> gen_col varchar ( 10 ) generated always as (
-> json_unquote( -- 使用 json_unquote 函数进行去掉双引号
-> json_extract(data , "$.name" )
-> )),
-> key idx(gen_col)
-> );
Query OK, 0 rows affected (0.13 sec)
mysql> show create table test_index_2;
-- -----省略表格线 -----
| test_index_2 | CREATE TABLE `test_index_2` (
`data` json DEFAULT NULL ,
`gen_col` varchar ( 10 ) GENERATED ALWAYS AS (json_unquote(
json_extract( data , "$.name" )
)) VIRTUAL,
KEY `idx` ( `gen_col` )
) ENGINE =InnoDB DEFAULT CHARSET=utf8mb4 |
-- -----省略表格线 -----
1 row in set ( 0.00 sec)
mysql> insert into test_index_2( data ) values ( '{"name":"tom", "age":18, "address":"SH"}');
Query OK, 1 row affected (0.03 sec)
mysql> insert into test_index_2( data ) values ( '{"name":"jim", "age":28, "address":"SZ"}');
Query OK, 1 row affected (0.02 sec)
mysql> select json_extract( data ,"$.name" ) as username from test_index_2 where gen_col= "tom" ; -- 未加单引号
+----------+
| username |
+----------+
| "tom" | -- 可以找到数据
+----------+
1 row in set ( 0.00 sec)
mysql> explain select json_extract( data ,"$.name" ) as username from test_index_2 where gen_col= "tom" G
*************************** 1. row ***************************
id: 1
select_type: SIMPLE
table : test_index_
partitions: NULL
type: ref
possible_keys: idx -- 使用了 key idx
key : idx
key_len: 43
ref: const
rows : 1
filtered: 100.
Extra: NULL
1 row in set , 1 warning ( 0.00 sec)
• 修改已存在的表创建 JSON 索引
--
-- 使用之前的 user 表操作
--
mysql> show create table user ;
-- -----省略表格线 -----
| user | CREATE TABLE `user` (
`uid` int ( 11 ) NOT NULL AUTO_INCREMENT,
`data` json DEFAULT NULL ,
PRIMARY KEY ( `uid` )
) ENGINE =InnoDB AUTO_INCREMENT= 5 DEFAULT CHARSET =utf8mb4 |
-- -----省略表格线 -----
1 row in set ( 0.00 sec)
mysql> select * from user ;
+-----+------------------------------------------------------+
| uid | data |
+-----+------------------------------------------------------+
| 1 | {"age": 18, "name": "tom", "address": ["SZ", "BJ"]} |
| 2 | {"age": 28, "mail": "jim@163.com", "name": "jim"} |
| 4 | {"age": 33, "name": "jery", "email": "jery@163.com"} |
+-----+------------------------------------------------------+
mysql> alter table user
-> add user_name varchar( 32 )
-> generated always as (json_extract( data ,"$.name")) virtual;
Query OK, 0 rows affected (0.05 sec)
Records: 0 Duplicates: 0 Warnings: 0
-- virtual 关键字是不将该列的字段值存储，对应的是 stored
mysql> select user_name from user ;
+-----------+
| user_name |
+-----------+
| "tom" |
| "jim" |
| "jery" |
+-----------+
3 rows in set ( 0.00 sec)
mysql> alter table user add index idx(user_name);
Query OK, 0 rows affected (0.13 sec)
Records: 0 Duplicates: 0 Warnings: 0
mysql> select * from user where user_name= '"tom"' ; -- 加单引号
+-----+-----------------------------------------------------+-----------+
| uid | data | user_name |
+-----+-----------------------------------------------------+-----------+
| 1 | {"age": 18, "name": "tom", "address": ["SZ", "BJ"]} | "tom" |
+-----+-----------------------------------------------------+-----------+
1 row in set ( 0.00 sec)
mysql> explain select * from user where user_name= '"tom"' G
*************************** 1. row ***************************
id: 1
select_type: SIMPLE
table : user
partitions: NULL
type: ref
possible_keys: idx -- 使用了 key idx
key : idx
key_len: 131
ref: const
rows : 1
filtered: 100.
Extra: NULL
1 row in set , 1 warning ( 0.00 sec)
mysql> show create table user ;
-- -----省略表格线 -----
| user | CREATE TABLE `user` (
`uid` int ( 11 ) NOT NULL AUTO_INCREMENT,
`data` json DEFAULT NULL ,
`user_name` varchar ( 32 ) GENERATED ALWAYS AS (json_extract( data ,"$.name" )) VIRTUAL,
`user_name2` varchar ( 32 ) GENERATED ALWAYS AS (json_extract( data ,"$.name" )) VIRTUAL,
PRIMARY KEY ( `uid` ),
KEY `idx` ( `user_name` )
) ENGINE =InnoDB AUTO_INCREMENT= 5 DEFAULT CHARSET =utf8mb4 |
-- -----省略表格线 -----
1 row in set ( 0.00 sec)
二. 附录
--
-- 老师演示 JSON 的SQL
--
drop table if exists User ;
CREATE TABLE User (
uid BIGINT NOT NULL AUTO_INCREMENT PRIMARY KEY ,
name VARCHAR ( 32 ) NOT NULL ,
email VARCHAR( 256 ) NOT NULL ,
address VARCHAR ( 512 ) NOT NULL ,
UNIQUE KEY (name),
UNIQUE KEY (email)
);
INSERT INTO User VALUES ( NULL ,'David' ,'david@gmail' ,'Shanghai ...' );
INSERT INTO User VALUES ( NULL ,'Amy' ,'amy@gmail' ,'Beijing ...' );
INSERT INTO User VALUES ( NULL ,'Tom' ,'tom@gmail' ,'Guangzhou ...' );
SELECT * FROM User;
ALTER TABLE User ADD COLUMN address2 VARCHAR ( 512 ) NOT NULL ;
ALTER TABLE User ADD COLUMN passport VARCHAR ( 64 ) NOT NULL ;
DROP TABLE IF EXISTS UserJson;
CREATE TABLE UserJson(
uid BIGINT NOT NULL AUTO_INCREMENT PRIMARY KEY ,
data JSON
);
truncate table UserJson;
insert into UserJson
SELECT
uid,JSON_OBJECT( 'name' ,name, 'email' ,email, 'address' ,address) AS data
FROM
User ;
SELECT * FROM UserJson;
SELECT uid,JSON_EXTRACT( data ,'$.address2' ) from UserJson;
UPDATE UserJson
set data = json_insert( data ,"$.address2" ,"HangZhou ..." )
where uid = 1 ;
SELECT JSON_EXTRACT( data ,'$.address[1]' ) from UserJson;
select json_merge(JSON_EXTRACT( data ,'$.address' ) ,JSON_EXTRACT( data ,'$.address2' ))
from UserJson;
begin ;
UPDATE UserJson
set data = json_array_append( data ,"$.address" ,JSON_EXTRACT( data ,'$.address2' ))
where JSON_EXTRACT( data ,'$.address2' ) IS NOT NULL AND uid > 0 ;
select JSON_EXTRACT( data ,'$.address' ) from UserJson;
UPDATE UserJson
set data = JSON_REMOVE( data ,'$.address2' )
where uid> 0 ;
commit ;