用戶管理

創建用戶：CREATE USER
    CREATE USER ‘USERNAME‘@‘HOST‘ [IDENTIFIED BY ‘password‘]；
    默認權限：USAGE
    create user 創建完用戶之後它的權限很有限、創建完用戶之後是立即生效的
用戶重命名：RENAME USER
    RENAME USER old_user_name TO new_user_name
刪除用戶：
    DROP USER ‘USERNAME‘@‘HOST‘
    示例：刪除默認的空用戶
        DROP USER ‘‘@‘localhost‘;
修改密碼：
    mysql>SET PASSWORD FOR ‘user‘@‘host‘ = PASSWORD(‘password‘);
    mysql>UPDATE mysql.user SET password=PASSWORD(‘password‘) WHERE clause;
    此方法需要執行下面指令才能生效：
        mysql> FLUSH PRIVILEGES;
    #mysqladmin -u root -poldpass password ‘newpass‘
忘記管理員密碼的解決辦法：
    啟動mysqld進程時，為其使用如下選項：
        --skip-grant-tables --skip-networking
    使用UPDATE命令修改管理員密碼
    關閉mysqld進程，移除上述兩個選項，重啟mysqld
 

用戶管理示例：

查看系統表裏面的用戶：
    MariaDB [db1]> select user,host,password from mysql.user;
    +---------+---------------+-------------------------------------------+
    | user    | host          | password                                  |
    +---------+---------------+-------------------------------------------+
    | root    | localhost     | *A498955BAB852BEF5B0C78584202F0326BB117A7 |
    | root    | 127.0.0.1     | *A498955BAB852BEF5B0C78584202F0326BB117A7 |
    | cobbler | 192.168.137.% | *128977E278358FF80A246B5046F51043A2B1FCED |
    | mage    | 192.168.137.% | *128977E278358FF80A246B5046F51043A2B1FCED |
    +---------+---------------+-------------------------------------------+
創建一個用戶只允許單臺遠程主機IP能連接
    MariaDB [db1]> create user test@‘192.168.137.56‘ identified by ‘centos‘;
    Query OK, 0 rows affected (0.01 sec)
查看創建好的用戶
    MariaDB [db1]> select user,host,password from mysql.user;               
    +---------+----------------+-------------------------------------------+
    | user    | host           | password                                  |
    +---------+----------------+-------------------------------------------+
    | root    | localhost      | *A498955BAB852BEF5B0C78584202F0326BB117A7 |
    | root    | 127.0.0.1      | *A498955BAB852BEF5B0C78584202F0326BB117A7 |
    | test    | 192.168.137.56 | *128977E278358FF80A246B5046F51043A2B1FCED |
    | cobbler | 192.168.137.%  | *128977E278358FF80A246B5046F51043A2B1FCED |
    | mage    | 192.168.137.%  | *128977E278358FF80A246B5046F51043A2B1FCED |
    +---------+----------------+-------------------------------------------+
    5 rows in set (0.00 sec)
客戶端驗證此用戶
    [root@node6 ~mysql -utest -p -h192.168.137.57
    Enter password: 
    Welcome to the MariaDB monitor.  Commands end with ; or \g.
    Your MariaDB connection id is 12
    Server version: 10.2.15-MariaDB-log MariaDB Server

    Copyright (c) 2000, 2017, Oracle, MariaDB Corporation Ab and others.

    Type ‘help;‘ or ‘\h‘ for help. Type ‘\c‘ to clear the current input statement.

    MariaDB [(none)]> select user();
    +---------------------+
    | user()              |
    +---------------------+
    | [email protected] |
    +---------------------+
    1 row in set (0.00 sec)

刪除用戶：
    MariaDB [db1]> drop user mage@‘192.168.137.%‘;
    Query OK, 0 rows affected (0.00 sec)

    MariaDB [db1]> select user,host,password from mysql.user;
    +---------+----------------+-------------------------------------------+
    | user    | host           | password                                  |
    +---------+----------------+-------------------------------------------+
    | root    | localhost      | *A498955BAB852BEF5B0C78584202F0326BB117A7 |
    | root    | 127.0.0.1      | *A498955BAB852BEF5B0C78584202F0326BB117A7 |
    | test    | 192.168.137.56 | *128977E278358FF80A246B5046F51043A2B1FCED |
    | cobbler | 192.168.137.%  | *128977E278358FF80A246B5046F51043A2B1FCED |
    +---------+----------------+-------------------------------------------+
    4 rows in set (0.00 sec)
修改用戶密碼：
    # set 修改用戶密碼：
    MariaDB [db1]> set password for test@‘192.168.137.56‘=password(‘123456‘);
    Query OK, 0 rows affected (0.00 sec)

    # update 修改表的方式來修改密碼，不過需要手動來刷新
    MariaDB [db1]> update mysql.user set password=password(‘centos‘) where user=‘test‘;
    Query OK, 1 row affected (0.01 sec)
    Rows matched: 1  Changed: 1  Warnings: 0

    MariaDB [db1]> flush privileges;
    Query OK, 0 rows affected (0.00 sec)
 

MySQL權限管理

權限類別：
    管理類
    程序類
    數據庫級別
    表級別
    字段級別
管理類：
    CREATE TEMPORARY TABLES
    CREATE USER
    FILE
    SUPER
    SHOW DATABASES
    RELOAD
    SHUTDOWN
    REPLICATION SLAVE
    REPLICATION CLIENT
    LOCK TABLES
    PROCESS
程序類： 
    FUNCTION
    PROCEDURE
    TRIGGER
    CREATE
    ALTER
    DROP
    EXCUTE
庫和表級別：
    DATABASE
    TABLE
    ALTER
    CREATE
    CREATE VIEW
    DROP
    INDEX
    SHOW VIEW
    GRANT OPTION：能將自己獲得的權限轉贈給其他用戶
數據操作：
    SELECT
    INSERT
    DELETE
    UPDATE
字段級別：
    SELECT(col1,col2,...)
    UPDATE(col1,col2,...)
    INSERT(col1,col2,...)
所有權限：
    ALL PRIVILEGES 或 ALL
 

授權

參考：https://dev.mysql.com/doc/refman/5.7/en/grant.html
GRANT priv_type [(column_list)],... ON [object_type] priv_level TO ‘user‘@‘host‘ [IDENTIFIED BY ‘password‘] [WITH GRANT OPTION];
    priv_type: ALL [PRIVILEGES]
    object_type:TABLE | FUNCTION | PROCEDURE
    priv_level: *(所有庫) | *.* | db_name.* | db_name.tbl_name | tbl_name(當前庫的表) | db_name.routine_name(指定庫的函數,存儲過程,觸發器)
    with_option: GRANT OPTION
        | MAX_QUERIES_PER_HOUR count     # 限定在每個小時最多查詢多少次   
        | MAX_UPDATES_PER_HOUR count     # 限定每個小時最多更新多少次
        | MAX_CONNECTIONS_PER_HOUR count # 限定每個小時最多連接多少次
        | MAX_USER_CONNECTIONS count     # 限定每個小時用戶連接多少次
回收授權：
    REVOKE priv_type [(column_list)] [, priv_type [(column_list)]] ... ON [object_type] priv_level FROM user [, user] ...
查看指定用戶獲得的授權：
    Help SHOW GRANTS
    SHOW GRANTS FOR ‘user‘@‘host‘;
    SHOW GRANTS FOR CURRENT_USER[()];
註意：
    MariaDB服務進程啟動時會讀取mysql庫中所有授權表至內存
        (1) GRANT或REVOKE等執行權限操作會保存於系統表中，MariaDB的服務進程通常會自動重讀授權表，使之生效
        (2) 對於不能夠或不能及時重讀授權表的命令，可手動讓MariaDB的服務進程重讀授權表：mysql> FLUSH PRIVILEGES;

MySQL權限管理示例

創建test用戶
MariaDB [db1]> create user test@‘192.168.137.56‘ identified by ‘centos‘;

只授權select權限給test用戶
MariaDB [hellodb]> grant select(stuid,name) on hellodb.students to ‘test‘@‘192.168.137.56‘;
Query OK, 0 rows affected (0.00 sec)

在客戶端驗證：
    MariaDB [hellodb]> show databases;
    +--------------------+
    | Database           |
    +--------------------+
    | hellodb            |
    | information_schema |
    +--------------------+
    2 rows in set (0.00 sec)

    MariaDB [hellodb]> desc students;
    +-------+------------------+------+-----+---------+----------------+
    | Field | Type             | Null | Key | Default | Extra          |
    +-------+------------------+------+-----+---------+----------------+
    | StuID | int(10) unsigned | NO   | PRI | NULL    | auto_increment |
    | Name  | varchar(50)      | NO   |     | NULL    |                |
    +-------+------------------+------+-----+------。，---+----------------+
    2 rows in set (0.01 sec)

    MariaDB [hellodb]> select stuid,name from students;
取消權限：
    MariaDB [hellodb]> revoke SELECT (name,stuid) ON `hellodb`.`students` TO ‘test‘@‘192.168.137.56‘;

MySQL-用戶和權限管理