数据库的基本操作
创建数据库
//创建数据库
//语法：CREATE DATABASE [IF NOT EXISTS] 'DB_NAME';
//创建数据库wg
mysql> create database wg;
Query OK, 1 row affected (0.00 sec)
mysql> show databases;
+--------------------+
| Database |
+--------------------+
| information_schema |
| mysql |
| performance_schema |
| sys |
| wg |
+--------------------+
5 rows in set (0.00 sec)
//删除数据库
//语法：DROP DATABASE [IF EXISTS] 'DB_NAME';
//删除数据库wg
mysql> drop database wg;
Query OK, 0 rows affected (0.00 sec)
mysql> show databases;
+--------------------+
| Database |
+--------------------+
| information_schema |
| mysql |
| performance_schema |
| sys |
+--------------------+
4 rows in set (0.00 sec)
表操作
//创建表
//语法：CREATE TABLE table_name (col1 datatype 修饰符,col2 datatype 修饰符) ENGINE='存储引擎类型';
//在数据库wg里创建表game
mysql> use wg; //进入wg数据库
Database changed
mysql> create table game(id int NOT NULL,name varchar(100)NOT NULL,age tinyint);
Query OK, 0 rows affected (0.00 sec) //创建一个game的表
//查看当前数据库中有哪些表
mysql> show tables;
+--------------+
| Tables_in_wg |
+--------------+
| game |
+--------------+
1 row in set (0.00 sec)
//删除表
//语法：DROP TABLE [ IF EXISTS ] 'table_name';
//删除表game
mysql> DROP TABLE game;
Query OK, 0 rows affected (0.01 sec)
mysql> show tables;
Empty set (0.00 sec)
用户操作
mysql用户帐号由两部分组成，如'USERNAME'@'HOST'，表示此USERNAME只能从此HOST上远程登录
这里（'USERNAME'@'HOST'）的HOST用于限制此用户可通过哪些主机远程连接mysql程序，其值可为：
- IP地址，如：172.16.12.129
- 通配符
- %：匹配任意长度的任意字符，常用于设置允许从任何主机登录
- _：匹配任意单个字符
//数据库用户创建
//语法：CREATE USER 'game'@'host' [IDENTIFIED BY 'password'];
//创建数据库用户game
mysql> CREATE USER 'wg'@'192.168.78.136' IDENTIFIED BY 'Wg1234!';
Query OK, 0 rows affected (0.00 sec)
//使用新创建的用户和密码登录
[root@localhost ~]# mysql -uwg -pWg1234! -h192.168.78.136
mysql: [Warning] Using a password on the command line interface can be insecure.
Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 6
Server version: 5.7.23 MySQL Community Server (GPL)
Copyright (c) 2000, 2018, Oracle and/or its affiliates. All rights reserved.
Oracle is a registered trademark of Oracle Corporation and/or its
affiliates. Other names may be trademarks of their respective
owners.
Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.
mysql>
//删除数据库用户
//语法：DROP USER 'game'@'host';
mysql> DROP USER 'wg'@'192.168.78.136';
Query OK, 0 rows affected (0.00 sec)
查看命令SHOW
//查看支持的所有字符集
mysql> SHOW CHARACTER SET;
+----------+---------------------------------+---------------------+--------+
| Charset | Description | Default collation | Maxlen |
+----------+---------------------------------+---------------------+--------+
| big5 | Big5 Traditional Chinese | big5_chinese_ci | 2 |
| dec8 | DEC West European | dec8_swedish_ci | 1 |
| cp850 | DOS West European | cp850_general_ci | 1 |
| hp8 | HP West European | hp8_english_ci | 1 |
| koi8r | KOI8-R Relcom Russian | koi8r_general_ci | 1 |
| latin1 | cp1252 West European | latin1_swedish_ci | 1 |
| latin2 | ISO 8859-2 Central European | latin2_general_ci | 1 |
| swe7 | 7bit Swedish | swe7_swedish_ci | 1 |
| ascii | US ASCII | ascii_general_ci | 1 |
| ujis | EUC-JP Japanese | ujis_japanese_ci | 3 |
| sjis | Shift-JIS Japanese | sjis_japanese_ci | 2 |
| hebrew | ISO 8859-8 Hebrew | hebrew_general_ci | 1 |
| tis620 | TIS620 Thai | tis620_thai_ci | 1 |
| euckr | EUC-KR Korean | euckr_korean_ci | 2 |
| koi8u | KOI8-U Ukrainian | koi8u_general_ci | 1 |
| gb2312 | GB2312 Simplified Chinese | gb2312_chinese_ci | 2 |
| greek | ISO 8859-7 Greek | greek_general_ci | 1 |
| cp1250 | Windows Central European | cp1250_general_ci | 1 |
| gbk | GBK Simplified Chinese | gbk_chinese_ci | 2 |
| latin5 | ISO 8859-9 Turkish | latin5_turkish_ci | 1 |
| armscii8 | ARMSCII-8 Armenian | armscii8_general_ci | 1 |
| utf8 | UTF-8 Unicode | utf8_general_ci | 3 |
| ucs2 | UCS-2 Unicode | ucs2_general_ci | 2 |
| cp866 | DOS Russian | cp866_general_ci | 1 |
| keybcs2 | DOS Kamenicky Czech-Slovak | keybcs2_general_ci | 1 |
| macce | Mac Central European | macce_general_ci | 1 |
| macroman | Mac West European | macroman_general_ci | 1 |
| cp852 | DOS Central European | cp852_general_ci | 1 |
| latin7 | ISO 8859-13 Baltic | latin7_general_ci | 1 |
| utf8mb4 | UTF-8 Unicode | utf8mb4_general_ci | 4 |
| cp1251 | Windows Cyrillic | cp1251_general_ci | 1 |
| utf16 | UTF-16 Unicode | utf16_general_ci | 4 |
| utf16le | UTF-16LE Unicode | utf16le_general_ci | 4 |
| cp1256 | Windows Arabic | cp1256_general_ci | 1 |
| cp1257 | Windows Baltic | cp1257_general_ci | 1 |
| utf32 | UTF-32 Unicode | utf32_general_ci | 4 |
| binary | Binary pseudo charset | binary | 1 |
| geostd8 | GEOSTD8 Georgian | geostd8_general_ci | 1 |
| cp932 | SJIS for Windows Japanese | cp932_japanese_ci | 2 |
| eucjpms | UJIS for Windows Japanese | eucjpms_japanese_ci | 3 |
| gb18030 | China National Standard GB18030 | gb18030_chinese_ci | 4 |
+----------+---------------------------------+---------------------+--------+
41 rows in set (0.00 sec)
//查看当前数据库支持的所有存储引擎
mysql> SHOW ENGINES;
+--------------------+---------+----------------------------------------------------------------+--------------+------+------------+
| Engine | Support | Comment | Transactions | XA | Savepoints |
+--------------------+---------+----------------------------------------------------------------+--------------+------+------------+
| InnoDB | DEFAULT | Supports transactions, row-level locking, and foreign keys | YES | YES | YES |
| MRG_MYISAM | YES | Collection of identical MyISAM tables | NO | NO | NO |
| MEMORY | YES | Hash based, stored in memory, useful for temporary tables | NO | NO | NO |
| BLACKHOLE | YES | /dev/null storage engine (anything you write to it disappears) | NO | NO | NO |
| MyISAM | YES | MyISAM storage engine | NO | NO | NO |
| CSV | YES | CSV storage engine | NO | NO | NO |
| ARCHIVE | YES | Archive storage engine | NO | NO | NO |
| PERFORMANCE_SCHEMA | YES | Performance Schema | NO | NO | NO |
| FEDERATED | NO | Federated MySQL storage engine | NULL | NULL | NULL |
+--------------------+---------+----------------------------------------------------------------+--------------+------+------------+
9 rows in set (0.00 sec)
表内容的增删改查
DML操作包括增(INSERT)、删(DELETE)、改(UPDATE)、查(SELECT)，均属针对表的操作。
//创建一个game的表
mysql> create table game(id int(11) not null primary key auto_increment,name varchar(100) not null,age tinyint(4));
Query OK, 0 rows affected (0.01 sec)
mysql> desc game; //查看表
+-------+--------------+------+-----+---------+----------------+
| Field | Type | Null | Key | Default | Extra |
+-------+--------------+------+-----+---------+----------------+
| id | int(11) | NO | PRI | NULL | auto_increment |
| name | varchar(100) | NO | | NULL | |
| age | tinyint(4) | YES | | NULL | |
+-------+--------------+------+-----+---------+----------------+
3 rows in set (0.01 sec)
//增加表的内容
mysql> insert game (name,age) values ('zhangsan',12),('lisi',15),('wangwu',17);
Query OK, 3 rows affected (0.01 sec)
Records: 3 Duplicates: 0 Warnings: 0
//查看表的内容
mysql> select * from game;
+----+----------+------+
| id | name | age |
+----+----------+------+
| 1 | zhangsan | 12 |
| 2 | lisi | 15 |
| 3 | wangwu | 17 |
+----+----------+------+
3 rows in set (0.00 sec)
//删除表的内容
mysql> delete from game where age=17;
Query OK, 1 row affected (0.00 sec)
mysql> select * from game;
+----+----------+------+
| id | name | age |
+----+----------+------+
| 1 | zhangsan | 12 |
| 2 | lisi | 15 |
+----+----------+------+
2 rows in set (0.00 sec)
//修改表的内容
mysql> update game set age=50 where name='zhangsan';
Query OK, 1 row affected (0.00 sec)
Rows matched: 1 Changed: 1 Warnings: 0
mysql> select * from game;
+----+----------+------+
| id | name | age |
+----+----------+------+
| 1 | zhangsan | 50 |
| 2 | lisi | 15 |
+----+----------+------+
2 rows in set (0.00 sec)
mysql>
alter结构的添加、删除、修改
mysql> desc home; //新创建home表
+-------+--------------+------+-----+---------+----------------+
| Field | Type | Null | Key | Default | Extra
|+-------+--------------+------+-----+---------+----------------+
| id | int(11) | NO | PRI | NULL | auto_increment |
| name | varchar(100) | NO | | NULL | |
| age | tinyint(4) | YES | | NULL | |
+-------+--------------+------+-----+---------+----------------+
3 rows in set (0.00 sec)mysql> select * from home order by id desc;
+----+----------+------+
| id | name | age |
+----+----------+------+
| 5 | zhaosi | 19 |
| 4 | libai | 14 |
| 3 | wangwu | 17 |
| 2 | lisi | 15 |
| 1 | zhangsan | 12 |
+----+----------+------+
5 rows in set (0.00 sec)
//添加表结构mysql> alter table home add column dengji int(3);
Query OK, 0 rows affected (0.04 sec)
Records: 0 Duplicates: 0 Warnings: 0
mysql> select * from home;
+----+----------+------+--------+
| id | name | age | dengji |
+----+----------+------+--------+
| 1 | zhangsan | 12 | NULL |
| 2 | lisi | 15 | NULL |
| 3 | wangwu | 17 | NULL |
| 4 | libai | 14 | NULL |
| 5 | zhaosi | 19 | NULL |
+----+----------+------+--------+5 rows in set (0.00 sec)
mysql> alter table home add column nianling int(3) after id; //在id后面添加一列
Query OK, 0 rows affected (0.07 sec)Records: 0 Duplicates: 0 Warnings: 0
mysql> select * from home;
+----+----------+----------+------+--------+
| id | nianling | name | age | dengji |
+----+----------+----------+------+--------+
| 1 | NULL | zhangsan | 12 | NULL |
| 2 | NULL | lisi | 15 | NULL |
| 3 | NULL | wangwu | 17 | NULL |
| 4 | NULL | libai | 14 | NULL |
| 5 | NULL | zhaosi | 19 | NULL |
+----+----------+----------+------+--------+
5 rows in set (0.00 sec)
//删除表结构mysql> alter table home drop column nianling;
Query OK, 0 rows affected (0.03 sec)
Records: 0 Duplicates: 0 Warnings: 0
mysql> select * from home;
+----+----------+------+--------+
| id | name | age | dengji |
+----+----------+------+--------+
| 1 | zhangsan | 12 | NULL |
| 2 | lisi | 15 | NULL |
| 3 | wangwu | 17 | NULL |
| 4 | libai | 14 | NULL |
| 5 | zhaosi | 19 | NULL |
+----+----------+------+--------+
5 rows in set (0.00 sec)
//修改表的结构mysql> alter table home modify id varchar(30);
Query OK, 5 rows affected (0.03 sec)Records: 5 Duplicates: 0 Warnings: 0
mysql> desc home;
+--------+--------------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra
|+--------+--------------+------+-----+---------+-------+
| id | varchar(30) | NO | PRI | NULL | |
| name | varchar(100) | NO | | NULL | |
| age | tinyint(4) | YES | | NULL | |
| dengji | int(3) | YES | | NULL | |
+--------+--------------+------+-----+---------+-------+
4 rows in set (0.01 sec)
数据库的授权
创建授权grant
权限类型(priv_type)
| 权限类型 | 代表什么？ |
|---|---|
| ALL | 所有权限 |
| SELECT | 读取内容的权限 |
| INSERT | 插入内容的权限 |
| UPDATE | 更新内容的权限 |
| DELET 删除内容的权限 |
指定要操作的对象db_name.table_name
| 表示方式 | 意义 |
|---|---|
| . | 所有库的所有表 |
| db_name | 指定库的所有表 |
| db_name.table_name | 指定库的指定表 |
WITH GRANT OPTION：被授权的用户可将自己的权限副本转赠给其他用户，说白点就是将自己的权限完全复制给另一个用户。不建议使用。
查看授权
//查看当前登录用户的授权信息
mysql> show grants;
+---------------------------------------------------------------------+
| Grants for root@localhost |
+---------------------------------------------------------------------+
| GRANT ALL PRIVILEGES ON *.* TO 'root'@'localhost' WITH GRANT OPTION |
| GRANT PROXY ON ''@'' TO 'root'@'localhost' WITH GRANT OPTION |
+---------------------------------------------------------------------+
2 rows in set (0.00 sec)
//查看指定用户wg的授权信息
mysql> SHOW GRANTS FOR wg;
+-----------------------------------------------+
| Grants for wg@% |
+-----------------------------------------------+
| GRANT ALL PRIVILEGES ON *.* TO 'wg'@'%' |
+-----------------------------------------------+
1 row in set (0.00 sec)mysql> SHOW GRANTS FOR 'wg'@'localhost';
+-------------------------------------------------------+
| Grants for wg@localhost |
+-------------------------------------------------------+
| GRANT ALL PRIVILEGES ON *.* TO 'wg'@'localhost' |
+-------------------------------------------------------+
1 row in set (0.00 sec)mysql> SHOW GRANTS FOR 'wg'@'192.168.78.136';
+-------------------------------------------------------+
| Grants for wg@192.168.78.136 |
+-------------------------------------------------------+
| GRANT ALL PRIVILEGES ON *.* TO 'wg'@'192.168.78.136' |
+-------------------------------------------------------+
1 row in set (0.00 sec)
取消授权REVOKE
//语法：REVOKE priv_type,... ON db_name.table_name FROM 'username'@'host';
mysql> REVOKE ALL ON *.* FROM 'wg'@'192.168.78.136';
Query OK, 0 rows affected (0.00 sec)
mysql> FLUSH PRIVILEGES;
Query OK, 0 rows affected (0.00 sec)
注意：mysql服务进程启动时会读取mysql库中的所有授权表至内存中：
- GRANT或REVOKE等执行权限操作会保存于表中，mysql的服务进程会自动重读授权表，并更新至内存中
- 对于不能够或不能及时重读授权表的命令，可手动让mysql的服务进程重读授权表
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