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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。

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

本文由 LCTT 原创翻译,Linux中国 荣誉推出

最新评论

我也要发表评论

Vito 2014-01-07 10:39 回复
必须知道的基础知识                  
koolar 2014-01-08 14:03 回复
都是最基础的知识啊!
upall 2014-01-08 17:39 7 回复
有了一种DBA很弱的感觉。。。。
我叫冉小艺 2014-01-09 16:10 3 回复

select count(*) from table_name; count(*)会滤掉空值,有可能统计行数小于真实的行?

巴斯光年 2014-01-13 11:12 回复
回复 我叫冉小艺 的帖子

高手~~怎么破?
游客 2015-09-02 14:35 回复
问题1:默认的安装路径: /var/run/mysqld/mysqld.sock  还可以,  socket文件 改变路径了,这命令 就不行了
Suci 2015-09-09 09:38 回复
学习了~ 感谢楼主分享~
游客 2015-09-09 17:54 回复
也太基础了吧。。。
游客 2015-09-10 01:33 回复
我日,全中
shajia19841024 2015-12-19 16:02 回复
基础才是关键何阿
robin 2016-03-23 14:33 回复
怎么收藏文章啊
code_ct 2016-04-27 17:08 回复
这不是数据库基础知识吗
游客 2016-04-29 07:18 回复
Dba 都是饭桶吧
[1]
发表于 2016-04-29 07:18 的评论:
Dba 都是饭桶吧
游客 2016-05-12 14:08 回复
应该是吧,笑屎了
游客 2016-06-13 18:30 回复
应该深一点吧!
游客 2016-06-13 18:30 回复
应该深一点吧!
[1]
巴斯光年 发表于 2014-01-13 11:12 的评论:
回复 我叫冉小艺 的帖子

高手~~怎么破?
游客 2016-10-11 08:58 回复
设计符合三范式怎么会出现空行呢

LCTT 译者

bazz2 🌟 🌟 🌟 🌟
共计翻译: 59 篇 | 共计贡献: 1084
贡献时间:2013-10-10 -> 2016-09-27
访问我的 LCTT 主页 | 在 GitHub 上关注我

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