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、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

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。

1. root@localhost:/home/avi# service mysql status
3. /usr/bin/mysqladmin Ver 8.42 Distrib 5.1.72, for debian-linux-gnu on i486
4. Copyright (c) 2000, 2013, Oracle and/or its affiliates. All rights reserved.
6. Oracle is a registered trademark of Oracle Corporation and/or its
7. affiliates. Other names may be trademarks of their respective
8. owners.
10. Server version 5.1.72-2
11. Protocol version 10
12. Connection Localhost via UNIX socket
13. UNIX socket /var/run/mysqld/mysqld.sock
14. Uptime: 1 hour 22 min 49 sec
16. 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。

1. root@localhost:/home/avi# service mysql stop
3. Stopping MySQL database server: mysqld.
5. root@localhost:/home/avi# service mysql start
7. Starting MySQL database server: mysqld.
9. 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

1. root@localhost:/home/avi# mysql -u root -p
2. Enter password:
3. Welcome to the MySQL monitor. Commands end with ; or g.
4. Your MySQL connection id is 207
5. Server version: 5.1.72-2 (Debian)
7. Copyright (c) 2000, 2013, Oracle and/or its affiliates. All rights reserved.
9. Oracle is a registered trademark of Oracle Corporation and/or its
10. affiliates. Other names may be trademarks of their respective
11. owners.
13. Type 'help;' or 'h' for help. Type 'c' to clear the current input statement.
15. mysql>

问题4：如何列出所有数据库？

答案：运行命令 show databases;

1. mysql> show databases;
2. +--------------------+
3. | Database |
4. +--------------------+
5. | information_schema |
6. | a1 |
7. | cloud |
8. | mysql |
9. | phpmyadmin |
10. | playsms |
11. | sisso |
12. | test |
13. | ukolovnik |
14. | wordpress |
15. +--------------------+
16. 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。

1. mysql> use cloud;
2. Reading table information for completion of table and column names
3. You can turn off this feature to get a quicker startup with -A
5. Database changed
6. 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;

1. mysql> show tables;
2. +----------------------------+
3. | Tables_in_cloud |
4. +----------------------------+
5. | oc_appconfig |
6. | oc_calendar_calendars |
7. | oc_calendar_objects |
8. | oc_calendar_repeat |
9. | oc_calendar_share_calendar |
10. | oc_calendar_share_event |
11. | oc_contacts_addressbooks |
12. | oc_contacts_cards |
13. | oc_fscache |
14. | oc_gallery_sharing |
15. +----------------------------+
16. 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;

1. mysql> describe oc_users;
2. +----------+--------------+------+-----+---------+-------+
3. | Field | Type | Null | Key | Default | Extra |
4. +----------+--------------+------+-----+---------+-------+
5. | uid | varchar(64) | NO | PRI | | |
6. | password | varchar(255) | NO | | | |
7. +----------+--------------+------+-----+---------+-------+
8. 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;

1. mysql> drop table lookup;
3. 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;

1. mysql> drop database a1;
3. 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;

1. mysql> select * from engines;
2. +------------+---------+----------------------------------------------------------------+--------------+------+------------+
3. | ENGINE | SUPPORT | COMMENT | TRANSACTIONS | XA | SAVEPOINTS |
4. +------------+---------+----------------------------------------------------------------+--------------+------+------------+
5. | InnoDB | YES | Supports transactions, row-level locking, and foreign keys | YES | YES | YES |
6. | MRG_MYISAM | YES | Collection of identical MyISAM tables | NO | NO | NO |
7. | BLACKHOLE | YES | /dev/null storage engine (anything you write to it disappears) | NO | NO | NO |
8. | CSV | YES | CSV storage engine | NO | NO | NO |
9. | MEMORY | YES | Hash based, stored in memory, useful for temporary tables | NO | NO | NO |
10. | FEDERATED | NO | Federated MySQL storage engine | NULL | NULL | NULL |
11. | ARCHIVE | YES | Archive storage engine | NO | NO | NO |
12. | MyISAM | DEFAULT | Default engine as of MySQL 3.23 with great performance | NO | NO | NO |
13. +------------+---------+----------------------------------------------------------------+--------------+------+------------+
14. 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;

1. mysql> select uid from oc_users;
2. +-----+
3. | uid |
4. +-----+
5. | avi |
6. +-----+
7. 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”;

1. mysql> select create_time, engine from xyz where engine="MyIsam";
3. +---------------------+--------+
4. | create_time | engine |
5. +---------------------+--------+
6. | 2013-12-15 13:43:27 | MyISAM |
7. | 2013-12-15 13:43:27 | MyISAM |
8. | 2013-12-15 13:43:27 | MyISAM |
9. | 2013-12-15 13:43:27 | MyISAM |
10. | 2013-12-15 13:43:27 | MyISAM |
11. | 2013-12-15 13:43:27 | MyISAM |
12. | 2013-12-15 13:43:27 | MyISAM |
13. | 2013-12-15 13:43:27 | MyISAM |
14. | 2013-10-23 14:56:38 | MyISAM |
15. | 2013-10-23 14:56:38 | MyISAM |
16. | 2013-10-23 14:56:38 | MyISAM |
17. | 2013-10-23 14:56:38 | MyISAM |
18. | 2013-10-23 14:56:38 | MyISAM |
19. | 2013-10-23 14:56:38 | MyISAM |
20. | 2013-10-23 14:56:38 | MyISAM |
21. +---------------------+--------+
22. 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”;

1. mysql> select * from xrt where name = "tecmint" and web_address = “tecmint.com”;
2. +---------------+---------------------+---------------+
3. | Id | name | web_address |
4. +---------------+---------------------+----------------+
5. | 13 | tecmint | tecmint.com |
6. +---------------+---------------------+----------------+
7. | 41 | tecmint | tecmint.com |
8. +---------------+---------------------+----------------+

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";

1. mysql> select * from xrt where name != ”tecmint” and web_address = ”tecmint.com”;
3. +---------------+---------------------+---------------+
4. | Id | name | web_address |
5. +---------------+---------------------+----------------+
6. | 1173 | tecmint | tecmint.com |
7. +---------------+---------------------+----------------+

问题15：如何知道表内行数？

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

1. mysql> select count(*) from Tables;
3. +----------+
4. | count(*) |
5. +----------+
6. | 282 |
7. +----------+
8. 1 row in set (0.01 sec)

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原文发布时间为：2014-01-05

本文来自云栖社区合作伙伴“Linux中国”