15个 MySQL 基础面试题,DBA 们准备好了吗?

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此前我们已经有发表过Linux 面试基础问答之一、二和三共3篇文章,获得读者的好评,同时我们得到反馈,有些读者希望这种交互式学习方法能够做得更加灵活。心动不如行动,我们这就为您奉上 15个 MySQL 面试题

15个 MySQL 基础面试题,DBA 们准备好了吗?

问题1:你如何确定 MySQL 是否处于运行状态?

答案: Debian 上运行命令 service mysql status,在RedHat 上运行命令 service mysqld status。然后看看输出即可。

 

  root@localhost:/home/avi# service mysql status    /usr/bin/mysqladmin  Ver 8.42 Distrib 5.1.72, for debian-linux-gnu on i486  Copyright (c) 2000, 2013, Oracle and/or its affiliates. All rights reserved.    Oracle is a registered trademark of Oracle Corporation and/or its  affiliates. Other names may be trademarks of their respective  owners.    Server version 5.1.72-2  Protocol version 10  Connection Localhost via UNIX socket  UNIX socket /var/run/mysqld/mysqld.sock  Uptime: 1 hour 22 min 49 sec    Threads: 1  Questions: 112138  Slow queries: 1  Opens: 1485  Flush tables: 1  Open tables: 64  Queries per second avg: 22.567.

问题2:如何开启或停止 MySQL 服务?

答案:运行命令 service mysqld start 开启服务;运行命令 service mysqld stop 停止服务。

 

  root@localhost:/home/avi# service mysql stop    Stopping MySQL database server: mysqld.    root@localhost:/home/avi# service mysql start    Starting MySQL database server: mysqld.    Checking for corrupt, not cleanly closed and upgrade needing tables..  

问题3:如何通过 Shell 登入 MySQL?

答案:运行命令 mysql -u root -p

 

  root@localhost:/home/avi# mysql -u root -p   Enter password:   Welcome to the MySQL monitor.  Commands end with ; or /g.   Your MySQL connection id is 207   Server version: 5.1.72-2 (Debian)     Copyright (c) 2000, 2013, Oracle and/or its affiliates. All rights reserved.     Oracle is 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>  

问题4:如何列出所有数据库?

答案:运行命令 show databases;

 

  mysql> show databases;   +--------------------+   | Database           |   +--------------------+   | information_schema |   | a1                 |   | cloud              |   | mysql              |   | phpmyadmin         |   | playsms            |   | sisso              |   | test               |   | ukolovnik          |   | wordpress          |   +--------------------+   10 rows in set (0.14 sec)  

问题5: 如何切换到某个数据库并在上面工作?

答案:运行命令 use database_name; 进入名为 database_name 的数据库。

 

  mysql> use cloud;   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   mysql>  

问题6:如何列出某个数据库内所有表?

答案:在当前数据库运行命令 show tables;

 

  mysql> show tables;   +----------------------------+   | Tables_in_cloud            |   +----------------------------+   | oc_appconfig               |   | oc_calendar_calendars      |   | oc_calendar_objects        |   | oc_calendar_repeat         |   | oc_calendar_share_calendar |   | oc_calendar_share_event    |   | oc_contacts_addressbooks   |   | oc_contacts_cards          |   | oc_fscache                 |   | oc_gallery_sharing         |   +----------------------------+   10 rows in set (0.00 sec)  

问题7:如何获取表内所有 Field 对象的名称和类型?

答案:运行命令 describe table_name;

 

  mysql> describe oc_users;   +----------+--------------+------+-----+---------+-------+   | Field    | Type         | Null | Key | Default | Extra |   +----------+--------------+------+-----+---------+-------+   | uid      | varchar(64)  | NO   | PRI |         |       |   | password | varchar(255) | NO   |     |         |       |   +----------+--------------+------+-----+---------+-------+   2 rows in set (0.00 sec)  

问题8:如何删除表?

答案:运行命令 drop table table_name;

 

  mysql> drop table lookup;     Query OK, 0 rows affected (0.00 sec)  

问题9:如何删除数据库?

答案:运行命令 drop database database-name;

 

  mysql> drop database a1;     Query OK, 11 rows affected (0.07 sec)  

问题10:如何查看表内所有数据?

答案:运行命令 select * from table_name;

 

  mysql> select * from engines;   +------------+---------+----------------------------------------------------------------+--------------+------+------------+   | ENGINE     | SUPPORT | COMMENT                                                        | TRANSACTIONS | XA   | SAVEPOINTS |   +------------+---------+----------------------------------------------------------------+--------------+------+------------+   | InnoDB     | YES     | Supports transactions, row-level locking, and foreign keys     | YES          | YES  | YES        |   | MRG_MYISAM | YES     | Collection of identical MyISAM tables                          | NO           | NO   | NO         |   | BLACKHOLE  | YES     | /dev/null storage engine (anything you write to it disappears) | NO           | NO   | NO         |   | CSV        | YES     | CSV storage engine                                             | NO           | NO   | NO         |   | MEMORY     | YES     | Hash based, stored in memory, useful for temporary tables      | NO           | NO   | NO         |   | FEDERATED  | NO      | Federated MySQL storage engine                                 | NULL         | NULL | NULL       |   | ARCHIVE    | YES     | Archive storage engine                                         | NO           | NO   | NO         |   | MyISAM     | DEFAULT | Default engine as of MySQL 3.23 with great performance         | NO           | NO   | NO         |   +------------+---------+----------------------------------------------------------------+--------------+------+------------+   8 rows in set (0.00 sec)  

问题11:如何从表(比如 oc_users )中获取一个 field 对象(比如 uid)的所有数据?

答案:运行命令 select uid from oc_users;

 

  mysql> select uid from oc_users;   +-----+   | uid |   +-----+   | avi |   +-----+   1 row in set (0.03 sec)  

问题12:假设你有一个名为 ‘xyz’ 的表,它存在多个字段,如 ‘createtime’ 和 ‘engine’。名为 engine 的字段由 ‘Memoty’ 和 ‘MyIsam’ 两种数值组成。如何只列出 ‘createtime’ 和 ‘engine’ 这两列并且 engine 的值为 ‘MyIsam’?

答案:运行命令 select create_time, engine from xyz where engine = ”MyIsam”;

 

  mysql> select create_time, engine from xyz where engine="MyIsam";    +---------------------+--------+   | create_time         | engine |   +---------------------+--------+   | 2013-12-15 13:43:27 | MyISAM |   | 2013-12-15 13:43:27 | MyISAM |   | 2013-12-15 13:43:27 | MyISAM |   | 2013-12-15 13:43:27 | MyISAM |   | 2013-12-15 13:43:27 | MyISAM |   | 2013-12-15 13:43:27 | MyISAM |   | 2013-12-15 13:43:27 | MyISAM |   | 2013-12-15 13:43:27 | MyISAM |   | 2013-10-23 14:56:38 | MyISAM |   | 2013-10-23 14:56:38 | MyISAM |   | 2013-10-23 14:56:38 | MyISAM |   | 2013-10-23 14:56:38 | MyISAM |   | 2013-10-23 14:56:38 | MyISAM |   | 2013-10-23 14:56:38 | MyISAM |   | 2013-10-23 14:56:38 | MyISAM |   +---------------------+--------+   132 rows in set (0.29 sec)  

问题13:如何列出表 ‘xrt’ 内 name 域值为 ‘tecmint’,web_address 域值为 ‘tecmint.com’ 的所有数据?

答案:运行命令 select * from xrt where name = “tecmint” and web_address = “tecmint.com”;

 

  mysql> select  * from xrt where name = "tecmint" and web_address = “tecmint.com”;  +---------------+---------------------+---------------+   | Id                  | name                   | web_address |   +---------------+---------------------+----------------+   | 13                 |  tecmint               | tecmint.com  |  +---------------+---------------------+----------------+   | 41                 |  tecmint               | tecmint.com  |  +---------------+---------------------+----------------+  

问题14:如何列出表 ‘xrt’ 内 name 域值不为 ‘tecmint’,web_address 域值为 ‘tecmint.com’ 的所有数据?

答案:运行命令 select * from xrt where name != "tecmint" and web_address = "tecmint.com";

 

  mysql> select * from xrt where name != ”tecmint” and web_address = ”tecmint.com”;    +---------------+---------------------+---------------+   | Id            | name                | web_address   |   +---------------+---------------------+----------------+   | 1173          |  tecmint            | tecmint.com   |  +---------------+---------------------+----------------+  

问题15:如何知道表内行数?

答案:运行命令 select count(*) from table_name;

 

  mysql> select count(*) from Tables;     +----------+   | count(*) |   +----------+   |      282 |   +----------+   1 row in set (0.01 sec)  

以上是文章的全部内容。这篇‘Linux 面试题’对您有任何帮助吗?别忘了在下面留言,写出您的宝贵意见。


via: http://www.tecmint.com/basic-mysql-interview-questions-for-database-administrators/

译者:bazz2 校对:Caroline

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