一旦安装完成，MySQL 服务器应该自动启动。

sudo start mysql #手动的话这样启动

sudo stop mysql #手动停止

当你修改了配置文件后，你需要重启 mysqld 才能使这些修改生效。

要想检查 mysqld 进程是否已经开启，可以使用下面的命令：

pgrep mysqld

如果进程开启，这个命令将会返回该进程的 id。

MySQL配置文件：/etc/mysql/my.cnf ，其中指定了数据文件存放路径

datadir         = /var/lib/mysql

如果你创建了一个名为 test 的数据库，那么这个数据库的数据会存放到 /var/lib/mysql/test 目录下。 

进入MySQL

mysql -u root -p 

(输入mysql的root密码)

qii@ubuntu:~$ mysql -u root -p
Enter password: 
Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 37
Server version: 5.1.41-3ubuntu12.3 (Ubuntu)

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

mysql> 

修改 MySQL 的管理员密码：

sudo mysqladmin -u root password newpassword；

查看当前用户拥有的数据库：

mysql> show databases
-> ;
+--------------------+
| Database |
+--------------------+
| information_schema |
| mysql |
| performance_schema |
+--------------------+
3 rows in set (0.19 sec)

查看当前用户可以用的数据库：

mysql> show databases
-> ;
+--------------------+
| Database |
+--------------------+
| information_schema |
| mysql |
| performance_schema |
+--------------------+
3 rows in set (0.19 sec)

mysql> show tables
-> ;
ERROR 1046 (3D000): No database selected
mysql> select table_name from user_tables;
ERROR 1046 (3D000): No database selected
mysql> show databases;
+--------------------+
| Database |
+--------------------+
| information_schema |
| mysql |
| performance_schema |
+--------------------+
3 rows in set (0.00 sec)

选择一个当前数据库：

mysql> use mysql
Reading table information for completion of table and column names
You can turn off this feature to get a quicker startup with -A

Database changed

查看当前数据库中的表：
mysql> show tables
-> ;
+---------------------------+
| Tables_in_mysql |
+---------------------------+
| columns_priv |
| db |
| event |
| func |
| general_log |
| help_category |
| help_keyword |
| help_relation |
| help_topic |
| host |
| ndb_binlog_index |
| plugin |
| proc |
| procs_priv |
| proxies_priv |
| servers |
| slow_log |
| tables_priv |
| time_zone |
| time_zone_leap_second |
| time_zone_name |
| time_zone_transition |
| time_zone_transition_type |
| user |
+---------------------------+
24 rows in set (0.00 sec)

查看一个表的详细信息：

mysql> describe servers;
+-------------+----------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+-------------+----------+------+-----+---------+-------+
| Server_name | char(64) | NO | PRI | | |
| Host | char(64) | NO | | | |
| Db | char(64) | NO | | | |
| Username | char(64) | NO | | | |
| Password | char(64) | NO | | | |
| Port | int(4) | NO | | 0 | |
| Socket | char(64) | NO | | | |
| Wrapper | char(64) | NO | | | |
| Owner | char(64) | NO | | | |
+-------------+----------+------+-----+---------+-------+
9 rows in set (0.04 sec)