MySQL Basic question

Question 1: How do you determine if MySQL is running?

answer : Run command service mysql statuson Debian, Run command service mysqld statuson Redhat. Then look at the output.

[email protected]:/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. 

2: How do I turn on or stop the MySQL service?

answer : Run the command service mysqld start services; Run the command service mysqld stop service.

[Email protected]:/home/avi# service mysql stopstopping MySQL database server:mysqld. [Email protected]:/home/avi# service mysql startstarting MySQL database server:mysqld. Checking for corrupt, not cleanly closed and upgrade needing tables.

Question 3: How do I log in to MySQL via the Shell?

answer : Run command mysql-u root-p

[Email protected]:/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), and Oracle and/or its affiliates. All rights reserved. Oracle is a registered trademark of the Oracle Corporation and/or its affiliates. Other names trademarks of their respective owners. Type ' help ', ' or ' \h ' for help. Type ' \c ' to clear the current input statement. Mysql>

Question 4: How do I list all databases?

answer : Run the command show databases;

mysql> show databases; +--------------------+ | database            | +--------------------+ | information_schema |  | a1                  | | cloud               | | mysql              |  | phpmyadmin         | | playsms             | | sisso               | | test                | | ukolovnik           | | wordpress          | +-------------- ------+ 10 rows in set  (0.14 SEC)

Question 5: How do I switch to a database and work on it?

answer : Run command use database_name; Enter the database named database_name.

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>

Question 6: How do I list all the tables in a database?

answer : Run the command in the current database 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)

Question 7: How do I get the names and types of all Field objects in a table?

answer : Run command describe table_name;

mysql> describe oc_users; +-------- --+--------------+------+-----+---------+-------+ | field    | type          | Null | Key | Default |  extra | +----------+--------------+------+-----+---------+-------+ | uid       | varchar (  | NO   | PRI |   )       |       | | password |  varchar (255)  | NO   |     |          |       | +----------+--------------+--- ---+-----+---------+-------+ 2 rows in set  (0.00 sec) 

Question 8: How do I delete a table?

answer : Run command drop table table_name;

mysql> drop table lookup; Query OK, 0 rows Affected (0.00 sec)

Question 9: How do I delete a database?

answer : Run command drop database database-name;

mysql> drop DATABASE A1; Query OK, rows affected (0.07 sec)

Question 10: How can I view all the data in a table?

answer : Run command 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&nBsp;       | 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)

Question 11: How do I get all the data from a Field object (such as UID) from a table (such as Oc_users)?

answer : Run command select UID from oc_users;

Mysql> Select UID from oc_users; +-----+ | UID | +-----+ | Avi | +-----+ 1 row in Set (0.03 sec)

Question 12: Suppose you have a table named ' XYZ ', which has multiple fields, such as ' Create Time ' and ' engine '. The field named engine is made up of both ' memoty ' and ' MyIsam ' values. How to list only ' CreateTime ' and ' engine ' are the two columns and the engine value is ' MyIsam '?

answer : Run command 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)

Question 13: How do I list all data with the Name field value ' tecmint ' in table ' XRT ' and the web_address domain value ' tecmint.com '?

answer : Run command 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   |+---------------+---------------------+----------------+

Question 14: How do I list all the data in the table ' XRT ' where the Name field value is not ' tecmint ' and the web_address domain value is ' tecmint.com '?

answer : Run command 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 |+---------------+---------------------+----------------+

Question 15: How do I know the number of table insiders?

answer : Run command SELECT COUNT (*) from table_name;

Mysql> Select COUNT (*) from Tables; +----------+ | COUNT (*) |      +----------+ | 282 | +----------+ 1 row in Set (0.01 sec)

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MySQL Basic question