15个 MySQL 基础面试题，DBA 们准备好了吗？ ================================================================================ 此前我们已经有发表过Linux 面试基础问答之[一][1]、[二][2]和[三][3]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** ![](http://www.tecmint.com/wp-content/uploads/2013/12/Mysql-Interview-Questions.png) ### 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 ‘create_time’ 和 ‘engine’。名为 engine 的字段由 ‘Memoty’ 和 ‘MyIsam’ 两种数值组成。如何只列出 ‘create_time’ 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](https://github.com/bazz2) 校对：[Caroline](https://github.com/carolinewuyan) 本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创翻译，[Linux中国](http://linux.cn/) 荣誉推出 [1]:http://linux.cn/article-2315-1.html [2]:http://linux.cn/article-2370-1.html [3]:http://linux.cn/article-2371-1.html