15 Basic MySQL viðtalsspurningar fyrir gagnagrunnsstjóra
Fyrir þessa grein hafa þrjár greinar þegar verið birtar í „Linux Interview“ hlutanum og þær voru allar vel þegnar af athyglisverðum lesendum okkar, hins vegar fengum við endurgjöf til að gera þetta gagnvirka námsferli að hluta til. Frá hugmynd til aðgerða, við erum að veita þér 15 MySQL viðtalsspurningar.
[email :/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.
[email :/home/avi# service mysql stop Stopping MySQL database server: mysqld. [email :/home/avi# service mysql start Starting MySQL database server: mysqld. Checking for corrupt, not cleanly closed and upgrade needing tables..
[email :/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>
mysql> show databases; +--------------------+ | Database | +--------------------+ | information_schema | | a1 | | cloud | | mysql | | phpmyadmin | | playsms | | sisso | | test | | ukolovnik | | wordpress | +--------------------+ 10 rows in set (0.14 sec)
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>
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)
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)
mysql> drop table lookup; Query OK, 0 rows affected (0.00 sec)
mysql> drop database a1; Query OK, 11 rows affected (0.07 sec)
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)
mysql> select uid from oc_users; +-----+ | uid | +-----+ | avi | +-----+ 1 row in set (0.03 sec)
12. 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)
mysql> select * from xrt where name = "tecmint" and web_address = “linux-console.net”; +---------------+---------------------+---------------+ | Id | name | web_address | +---------------+---------------------+----------------+ | 13 | tecmint | linux-console.net | +---------------+---------------------+----------------+ | 41 | tecmint | linux-console.net | +---------------+---------------------+----------------+
mysql> select * from xrt where name != ”tecmint” and web_address = ”linux-console.net”; +---------------+---------------------+---------------+ | Id | name | web_address | +---------------+---------------------+----------------+ | 1173 | tecmint | linux-console.net | +---------------+---------------------+----------------+
mysql> select count(*) from Tables; +----------+ | count(*) | +----------+ | 282 | +----------+ 1 row in set (0.01 sec)
Það er allt í bili. Hvað finnst þér um þennan „Linux viðtalsspurning“ hluta. Ekki gleyma að veita okkur verðmæta endurgjöf þína í athugasemdahlutanum okkar.