mysql学习--基本使用

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)