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mysql sql应用_MySQL数据库应用（5）SQL语言（2）

發布時間：2025/4/16 数据库 32 豆豆

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三、刪除MySQL系統多余賬號

語法：drop user “user”@“主機域”? ?

四、創建MySQL用戶及賦予用戶權限

1、通過help查看grant命令幫助

1)通過在mysql中輸入“help grant”得到如下幫助信息

mysql>help grant

CREATE USER'jeffrey'@'localhost' IDENTIFIED BY 'mypass';

GRANT ALL ON db1.* TO 'jeffrey'@'localhost';

GRANT SELECT ON db2.invoice TO'jeffrey'@'localhost';

GRANT USAGE ON*.* TO 'jeffrey'@'localhost' WITH MAX_QUERIES_PER_HOUR 90;

通過查看grant的命令幫助，可以很容易的找到創建用戶并授權的例子！

2)運維人員比較常用的創建用戶的方法是，使用grant命令在創建用戶的同時進行權限授權。具體授權例子為：

grant all on db1.* to 'jeffrey'@'localhost' identified by 'mypass';

3)上述grant命令幫助里還提供了一個先用create命令創建用戶，然后再用grant授權的方法，即創建用戶和授權權限分開進行，例：

create user 'jeffrey'@'localhost' identified by 'mypass';

grant all on db1.* to 'jeffrey'@'localhost';

以上倆條命令相當于下面一條命令：

grant all on db1.* to 'jeffrey'@'loaclhost' identified by 'mypass';

2、通過grant命令創建用戶并授權

1)grant命令簡單語法如下：

grant all privilege on dbname.* username@'localhost' identified by 'passwd';

2)列表說明如下：

grant

all privilege

on dbname.*

to username@localhost

identified by 'passwd'

授權命令

對應權限

目標：庫和表

用戶名和客戶端主機

用戶密碼

說明：上述命令是授權localhost主機上通過用戶username管理dbname數據庫的所有權限，密碼為passwd。其中username，dbname，passwd可根據業務的情況修改。

3)操作案例1：創建oldboy用戶，對test庫具備所有權限，允許從localhost主機登陸管理數據庫，密碼是oldboy123。

mysql> select user,host frommysql.user;+------+-----------------------+

| user | host |

+------+-----------------------+

| root | 127.0.0.1 |

| root | ::1 |

| | localhost |

| root | localhost |

| | localhost.localdomain |

| root | localhost.localdomain |

+------+-----------------------+

6 rows in set (0.00sec)

mysql> grant all privileges on test.* to oldboy@'localhost' identified by 'oldboy123';

Query OK,0 rows affected (0.28sec)

mysql>flush privileges;

Query OK,0 rows affected (0.00sec)

mysql> select user,host frommysql.user;+--------+-----------------------+

| user | host |

+--------+-----------------------+

| root | 127.0.0.1 |

| root | ::1 |

| | localhost |

| oldboy | localhost |

| root | localhost |

| | localhost.localdomain |

| root | localhost.localdomain |

+--------+-----------------------+

7 rows in set (0.00 sec)

查看授權用戶oldboy具體權限

mysql> show grants foroldboy@localhost;+---------------------------------------------------------------------------------------------------------------+

| Grants for oldboy@localhost |

+---------------------------------------------------------------------------------------------------------------+

| GRANT USAGE ON *.* TO 'oldboy'@'localhost' IDENTIFIED BY PASSWORD '*FE28814B4A8B3309DAC6ED7D3237ADED6DA1E515' |

| GRANT ALL PRIVILEGES ON `test`.* TO 'oldboy'@'localhost' |

+---------------------------------------------------------------------------------------------------------------+

2 rows in set (0.00 sec)

3、create和grant配合法

1)首先創建用戶username及密碼passwd，授權主機localhost

create user 'username'@'localhost' identified by 'passwd';

2)然后授權localhost主機上通過用戶username管理dbname數據庫的所有權限，無需密碼。

grant all on dbname.* to 'username'@'loaclhost';

3)操作案例2：創建oldgirl用戶，對test庫具備所有權限，允許從localhost主機登陸管理數據庫，密碼是oldgirl123.

4)實戰演示

查看當前數據庫用戶情況，然后執行對應命令創建用戶如下：

mysql> create user oldgirl@localhost identified by 'oldgirl123';

Query OK,0 rows affected (0.00sec)

mysql> show grants foroldgirl@localhost;+----------------------------------------------------------------------------------------------------------------+

| Grants for oldgirl@localhost |

+----------------------------------------------------------------------------------------------------------------+

| GRANT USAGE ON *.* TO 'oldgirl'@'localhost' IDENTIFIED BY PASSWORD '*2CADADD54086D5EB4C9F10E0430084D7F179885C' |

+----------------------------------------------------------------------------------------------------------------+

1 row in set (0.00sec)

mysql> grant all on test.* to 'oldgirl'@'localhost';

Query OK,0 rows affected (0.00sec)

mysql> show grants foroldgirl@localhost;+----------------------------------------------------------------------------------------------------------------+

| Grants for oldgirl@localhost |

+----------------------------------------------------------------------------------------------------------------+

| GRANT USAGE ON *.* TO 'oldgirl'@'localhost' IDENTIFIED BY PASSWORD '*2CADADD54086D5EB4C9F10E0430084D7F179885C' |

| GRANT ALL PRIVILEGES ON `test`.* TO 'oldgirl'@'localhost' |

+----------------------------------------------------------------------------------------------------------------+

2 rows in set (0.00 sec)

4、授權局域網內主機遠程連接數據庫：

根據grant命令語法，我們知道test@‘localhost’位置為授權訪問數據庫的主機，localhost可以用域名，IP地址或IP段來替代，因此，要授權局域網內主機可以通過如下發放實現：

a.百分號匹配法

mysql> create user test@'10.0.0.%' identified by 'test';

Query OK,0 rows affected (0.00sec)

mysql>flush privileges;

Query OK,0 rows affected (0.00sec)

mysql>quit

Bye

[root@localhost~]# mysql -utest -ptest -h 10.0.0.7Welcome to the MySQL monitor. Commands end with ; or \g.

Your MySQL connection idis 8Server version:5.5.32Source distribution

Oracleis 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>

b.子網掩碼匹配法

mysql> create user test1@'10.0.0.0/255.255.255.0' identified by 'test1';

Query OK,0 rows affected (0.00sec)

mysql> select user,host frommysql.user;+---------+------------------------+

| user | host |

+---------+------------------------+

| test | 10.0.0.% |

| test1 | 10.0.0.0/255.255.255.0 |

| root | 127.0.0.1 |

| root | ::1 |

| | localhost |

| oldboy | localhost |

| oldgirl | localhost |

| root | localhost |

| | localhost.localdomain |

| root | localhost.localdomain |

+---------+------------------------+

10 rows in set (0.00sec)

mysql>quit

Bye

[root@localhost~]# mysql -utest1 -ptest1 -h 10.0.0.7Welcome to the MySQL monitor. Commands end with ; or \g.

Your MySQL connection idis 10Server version:5.5.32Source distribution

Oracleis 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>

通過mysql客戶端連接異地數據庫服務：

1)本地mysql -uroot -p‘oldboy123’ 連接數據庫相當于?mysql -uroot -p‘oldboy123’ -h localhost

2)要遠程連接10.0.0.7的數據庫，命令為mysql -utest -p‘test’ -h 10.0.0.7，如果要能成功連接，還需要在10.0.0.7的數據庫服務器上通過如下命令授權：

grant all on *.* to test@‘10.0.0.%’ identified by ‘test’；

3)通過php服務器連接mysql服務器的代碼寫法為；

//$link_id=mysql_connect('主機名','用戶','密碼')；

$link_id=mysql_connect('10.0.0.7','test','test') or mysql_error();if($link_id){

echo"musql successful by oldboy!";}else{

echo mysql_error();}

5、MySQL用戶可以授權的權限有哪些

1)先看看前面授權過的oldboy的權限

mysql> show grants for oldboy@localhost;

+---------------------------------------------------------------------------------------------- -----------------+

| Grants for oldboy@localhost |

+---------------------------------------------------------------------------------------------------------------+

| GRANT USAGE ON *.* TO 'oldboy'@'localhost' IDENTIFIED BY PASSWORD '*FE28814B4A8B3309DAC6ED7D3237ADED6DA1E515' |

| GRANT ALL PRIVILEGES ON `test`.* TO 'oldboy'@'localhost' |

+---------------------------------------------------------------------------------------------------------------+

2 rows in set (0.00 sec)

2)取消oldboy的只讀權限(SELECT)看看。

mysql> REVOKE INSERT ON test.* FROM 'oldboy'@'localhost';Query OK, 0 rows affected (0.00sec)

mysql> show grants for oldboy@localhost;+--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+

| Grants for oldboy@localhost |

+--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+

| GRANT USAGE ON *.* TO 'oldboy'@'localhost' IDENTIFIED BY PASSWORD '*FE28814B4A8B3309DAC6ED7D3237ADED6DA1E515' |

| GRANT SELECT, UPDATE, DELETE, CREATE, DROP, REFERENCES, INDEX, ALTER, CREATE TEMPORARY TABLES, LOCK TABLES, EXECUTE, CREATE VIEW, SHOW VIEW, CREATE ROUTINE, ALTER ROUTINE, EVENT,TRIGGER ON `test`.* TO 'oldboy'@'localhost' |

提示：此時我們再查看oldboy用戶權限，ALL PRIVILEGES 權限已經被細分了，但是沒有select權限了。

因為，我們可以得出結論，ALL PRIVILEGES包括權限為：

[root@localhost ~]# mysql -uroot -pdubin -e "show grants for oldboy@localhost;"|grep -i grant |tail -1 |tr ',' '\n' >all.txt[root@localhost ~]# cat all.txt -n1SELECT2INSERT3UPDATE4DELETE5CREATE6DROP7REFERENCES8INDEX9ALTER10CREATE TEMPORARY TABLES11LOCK TABLES12EXECUTE13CREATE VIEW14SHOW VIEW15CREATE ROUTINE16ALTER ROUTINE17EVENT18 TRIGGER

因此可以說，ALL PRIVILEGES的權限包括：

GRANT SELECT, UPDATE, DELETE, CREATE, DROP, REFERENCES, INDEX, ALTER, CREATE TEMPORARY TABLES, LOCK TABLES, EXECUTE, CREATE VIEW, SHOW VIEW, CREATE ROUTINE, ALTER ROUTINE, EVENT,TRIGGER ON `test`.* TO 'oldboy'@'localhost'

即在授權時，可以授權用戶最小的滿足業務需求的權限，而不是一味的授權“ALL PRIVILEGES”。

6、企業生產環境如何授權用戶權限？

1)博客，CMS等產品的數據庫授權：

對于web連接用戶授權盡量采用最小化原則，很多開源軟件都是web界面安裝，因此，在安裝期間除了select，insert，update，delete4個權限外，還需要create，drop等比較危險的權限。

mysql> grant select,insert,update,delete,create,drop on blog.* to 'blog'@'10.0.0.%' identified by 'oldboy';Query OK, 0 rows affected (0.00 sec)

常規情況下授權select，insert，update，delete4個權限即可，有的開源軟件，例如discuzbbs，還需要create，drop等比較危險的權限

2)生成數據庫表后，要收回create、drop授權：

mysql> grant select,insert,update,delete,create,drop on blog.* to 'blog'@'10.0.0.%' identified by 'oldboy';Query OK, 0 rows affected (0.00sec)

mysql> revoke create on blog.* from 'blog'@'10.0.0.%';Query OK, 0 rows affected (0.00sec)

mysql> show grants for blog@'10.0.0.%';+------------------------------------------------------------------------------------------------------------+

| Grants for blog@10.0.0.% |

+------------------------------------------------------------------------------------------------------------+

| GRANT USAGE ON *.* TO 'blog'@'10.0.0.%' IDENTIFIED BY PASSWORD '*7495041D24E489A0096DCFA036B166446FDDD992' |

| GRANT SELECT, INSERT, UPDATE, DELETE, DROP ON `blog`.* TO 'blog'@'10.0.0.%' |

+------------------------------------------------------------------------------------------------------------+2 rows in set (0.00 sec)

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