linux下MySQL初始环境设定
MySQL在刚刚被安装的时候，它的root用户是没有被设置密码的。首先来设置MySQL的root密码。[@more@]
[root@sample ~]# mysql -u root ← 用root用户登录MySQL服务器
Welcome to the MySQL monitor. Commands end with ; or g.
Your MySQL connection id is 2 to server version: 4.1.20
Type 'help;' or 'h' for help. Type 'c' to clear the buffer.
mysql> select user,host,password from mysql.user; ← 查看用户信息
+------+------------------------------+---------------+
| user | host | password |
+------+------------------------------+---------------+
| root | localhost | | ← root密码为空
| root | sample.centospub.com | | ← root密码为空
| | sample.centospub.com | |
| | localhost | |
+------+------------------------------+---------------+
4 rows in set (0.00 sec)
mysql> set password for root@localhost=password('在这里填入root密码'); ← 设置root密码
Query OK, 0 rows affected (0.01 sec)
mysql> set password for root@'sample.centospub.com'=password('在这里填入root密码'); ← 设置root密码
Query OK, 0 rows affected (0.01 sec)
mysql> select user,host,password from mysql.user; ← 查看用户信息
+------+--------------------------------+--------------------------+
| user | host | password |
+------+--------------------------------+--------------------------+
| root | localhost | 19b68057189b027f | ← root密码被设置
| root | sample.centospub.com | 19b68057189b027f | ← root密码被设置
| | sample.centospub.com | |
| | localhost | |
+------+--------------------------------+--------------------------+
4 rows in set (0.01 sec)
Bye
+++++++然后，测试一下root密码有没有生效。
[root@sample ~]# mysql -u root ← 通过空密码用root登录
ERROR 1045 (28000): Access denied for user 'root'@'localhost' (using password: NO) ← 出现此错误信息说明密码设置成功
[root@localhost ~]# mysql -u root -h sample.centospub.com ← 通过空密码用root登录
ERROR 1045 (28000): Access denied for user 'root'@'localhost' (using password: NO) ← 出现此错误信息说明密码设置成功
[root@sample ~]# mysql -u root -p ← 通过密码用root登录
Enter password: ← 在这里输入密码
Welcome to the MySQL monitor. Commands end with ; or g. ← 确认用密码能够成功登录
Your MySQL connection id is 5 to server version: 4.1.20
Type 'help;' or 'h' for help. Type 'c' to clear the buffer.
mysql> exit
Bye
[root@sample ~]# mysql -u root -h sample.centospub.com -p ← 通过密码用root登录
Enter password: ← 在这里输入密码
Welcome to the MySQL monitor. Commands end with ; or g. ← 确认用密码能够成功登录
Your MySQL connection id is 6 to server version: 4.1.20
Type 'help;' or 'h' for help. Type 'c' to clear the buffer.
mysql> exit ← 退出MySQL服务器Bye
++++++++++++++[2] 删除匿名用户
在MySQL刚刚被安装后，存在用户名、密码为空的用户。这使得数据库服务器有无需密码被登录的可能性。为消除隐患，将匿名用户删除。
[root@sample ~]# mysql -u root -p ← 通过密码用root登录
Enter password: ← 在这里输入密码
Welcome to the MySQL monitor. Commands end with ; or g.
Your MySQL connection id is 7 to server version: 4.1.20
Type 'help;' or 'h' for help. Type 'c' to clear the buffer.
mysql> select user,host from mysql.user; ← 查看用户信息
+------+----------------------------+
| user | host |
+------+----------------------------+
| | localhost |
| root | localhost |
| | sample.centospub.com |
| root | sample.centospub.com |
+------+----------------------------+
4 rows in set (0.02 sec)
mysql> delete from mysql.user where user=''; ← 删除匿名用户
Query OK, 2 rows affected (0.17 sec)
mysql> select user,host from mysql.user; ← 查看用户信息
+------+----------------------------+
| user | host |
+------+----------------------------+
| root | localhost |
| root | sample.centospub.com |
+------+----------------------------+
2 rows in set (0.00 sec)
Bye
+++++++++++++++++++[3] 删除测试用数据库
在MySQL被安装后，存在名为test的空数据库，将它删除。这里要注意的是，系统默认的还有一个名为mysql的数据库，它用于系统管理，所以请不要删除。
[root@sample ~]# mysql -u root -p ← 通过密码用root登录
Enter password: ← 在这里输入密码
Welcome to the MySQL monitor. Commands end with ; or g.
Your MySQL connection id is 8 to server version: 4.1.20
Type 'help;' or 'h' for help. Type 'c' to clear the buffer.
mysql> show databases; ← 查看系统已存在的数据库
+-------------+
| Database |
+-------------+
| mysql |
| test |
+------------+
2 rows in set (0.02 sec)
mysql> drop database test; ← 删除名为test的空数据库
Query OK, 0 rows affected (0.07 sec)
mysql> show databases; ← 查看系统已存在的数据库
+-------------+
| Database |
+-------------+
| mysql | ← 确认名为test的数据库被删除，已不存在
+-------------+
1 row in set (0.00 sec)
Bye
++++++++++++
测试MySQL
下面对MySQL进行测试。包括建立新用户，以及用对关系性数据库进行数据库操作的指令来试着建立数据库及数据表。这里，新建用户以centospub为例。
[root@sample ~]# mysql -u root -p ← 通过密码用root登录
Enter password: ← 在这里输入密码
Welcome to the MySQL monitor. Commands end with ; or g.
Your MySQL connection id is 9 to server version: 4.1.20
Type 'help;' or 'h' for help. Type 'c' to clear the buffer.
mysql> grant all privileges on test.* to centospub@localhost identified by '在这里定义密码'; ← 建立对test数据库有完全操作权限的名为centospub的用户
Query OK, 0 rows affected (0.03 sec)
mysql> select user from mysql.user where user='centospub'; ← 确认centospub用户的存在与否
+---------+
| user |
+---------+
| centospub | ← 确认centospub已经被建立
+---------+
1 row in set (0.01 sec)
mysql> exit ← 退出MySQL服务器
Bye
[root@sample ~]# mysql -u centospub -p ← 用新建立的centospub用户登录MySQL服务器
Enter password: ← 在这里输入密码
Welcome to the MySQL monitor. Commands end with ; or g.
Your MySQL connection id is 10 to server version: 4.1.20
Type 'help;' or 'h' for help. Type 'c' to clear the buffer.
mysql> create database test; ← 建立名为test的数据库
Query OK, 1 row affected (0.00 sec)
mysql> show databases; ← 查看系统已存在的数据库
+-------------+
| Database |
+-------------+
| test |
+-------------+
1 row in set (0.00 sec)
mysql> use test ← 连接到数据库
Database changed
mysql> create table test(num int, name varchar(50)); ← 在数据库中建立表
Query OK, 0 rows affected (0.03 sec)
mysql> show tables; ← 查看数据库中已存在的表
+-------------------+
| Tables_in_test |
+-------------------+
| test |
+-------------------+
1 row in set (0.01 sec)
mysql> insert into test values(1,'Hello World!'); ← 插入一个值到表中
Query OK, 1 row affected (0.02 sec)
mysql> select * from test; ← 查看数据库中的表的信息
+------+-------------------+
| num | name |
+------+-------------------+
| 1 | Hello World! |
+------+-------------------+
1 row in set (0.00 sec)
mysql> update test set name='Hello Everyone!'; ← 更新表的信息，赋予新的值
Query OK, 1 row affected (0.00 sec)
Rows matched: 1 Changed: 1 Warnings: 0
mysql> select * from test; ← 查看数据库中的表的信息
+------+----------------------+
| num | name |
+------+----------------------+
| 1 | Hello Everyone! | ← 确认被更新到新的值
+------+----------------------+
1 row in set (0.01 sec)
mysql> delete from test where num=1; ← 删除表内的值
Query OK, 1 row affected (0.00 sec)
mysql> select * from test; ← 确认删除结果
Empty set (0.01 sec)
mysql> drop table test; ← 删除表
Query OK, 0 rows affected (0.01 sec)
mysql> show tables; ← 查看表信息
Empty set (0.00 sec) ← 确认表已被删除
mysql> drop database test; ← 删除名为test的数据库
Query OK, 0 rows affected (0.01 sec)
mysql> show databases; ← 查看已存在的数据库
Empty set (0.01 sec) ← 确认test数据库已被删除（这里非root用户的关系，看不到名为mysql的数据库）
Bye
