15个 mysql 基础面试题,dba 们准备好了吗? - 高飞网
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15个 mysql 基础面试题,dba 们准备好了吗?

2014-01-19 01:25:37

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 i486Copyright (c) 2000, 2013, Oracle and/or its affiliates. All rights reserved.Oracle is a registered trademark of Oracle Corporation and/or itsaffiliates. Other names may be trademarks of their respectiveowners.Server version 5.1.72-2Protocol version 10Connection Localhost via UNIX socketUNIX socket /var/run/mysqld/mysqld.sockUptime: 1 hour 22 min 49 secThreads: 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 stopStopping MySQL database server: mysqld.root@localhost:/home/avi# service mysql startStarting 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 | YE | 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 |+—————+———————+—————-+ | 4 | 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。

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