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Monday, February 16, 2015

How to use MySQL from SSH (Linux shell)

Using MySQL from SSH may seem to be quite tricky if you’ve never done it before – but fear not – below is a list of MySQL commands that you can use to perform the required actions.
Start by logging-in using a SSH client, like PuTTY, to access the shell command line.
Below when you see # it means from the unix shell. And when you see mysql> it means from a MySQL prompt after logging into MySQL.
To login (from unix shell) use -h hostname only if needed
# mysql -h hostname -u root -p
This would ask you for a password and after providing the correct password you’d be logged-in to the MySQL prompt.
If you get an error with the above command then type # which mysql to make sure that mysql is installed properly and to find the directory. It would print out the mysql directory, and then you can use the above command as this: # [mysql dir]/bin/mysql -h hostname -u root -p
Create a database
mysql> create database [database name];
List all databases
mysql> show databases;
Switch to a database
mysql> use [database name];
To see all the tables in the selected database
mysql> show tables;
To see the database’s field formats
mysql> describe [table name];
To delete a database
mysql> drop database [database name];
To delete a table
mysql> drop table [table name];
Show all data in a table
mysql> SELECT * FROM [table name];
Show the columns and column information pertaining to the designated table
mysql> show columns from [table name];
Show certain selected rows with the value “whatever”
mysql> SELECT * FROM [table name] WHERE [field name] = "whatever";
Show all records containing the name “Bob” AND the phone number ’3444444′
mysql> SELECT * FROM [table name] WHERE name = "Bob" AND phone_number = '3444444';
Show all records not containing the name “Bob” AND the phone number ’3444444′ order by the phone_number field
mysql> SELECT * FROM [table name] WHERE name != "Bob" AND phone_number = '3444444' order by phone_number;
Show all records starting with the letters ‘bob’ AND the phone number ’3444444′
mysql> SELECT * FROM [table name] WHERE name like "Bob%" AND phone_number = '3444444';
Show all records starting with the letters ‘bob’ AND the phone number ’3444444′ limit to records 1 through 5
mysql> SELECT * FROM [table name] WHERE name like "Bob%" AND phone_number = '3444444' limit 1,5;
Use a regular expression to find records. Use “REGEXP BINARY” to force case-sensitivity. This finds any record beginning with a
mysql> SELECT * FROM [table name] WHERE rec RLIKE "^a";
Show unique records
mysql> SELECT DISTINCT [column name] FROM [table name];
Show selected records sorted in an ascending (asc) or descending (desc)
mysql> SELECT [col1],[col2] FROM [table name] ORDER BY [col2] DESC;
Return number of rows
mysql> SELECT COUNT(*) FROM [table name];
Sum column
mysql> SELECT SUM(*) FROM [table name];
Join tables on common columns
mysql> select lookup.illustrationid, lookup.personid,person.birthday from lookup left join person on lookup.personid=person.personid=statement to join birthday in person table with primary illustration id;
Creating a new user (login as root, switch to the MySQL db, make the user, update privs)
# mysql -u root -p
mysql> use mysql;
mysql> INSERT INTO user (Host,User,Password) VALUES('%','username',PASSWORD('password'));
mysql> flush privileges;

Change a user’s password from unix shell
# [mysql dir]/bin/mysqladmin -u username -h hostname.blah.org -p password 'new-password'
Change a user’s password from MySQL prompt (login as root, set the password, update privs)
# mysql -u root -p
mysql> SET PASSWORD FOR 'user'@'hostname' = PASSWORD('passwordhere');
mysql> flush privileges;

Recover a MySQL root password (stop the MySQL server process, start again with no grant tables, login to MySQL as root, set new password, exit MySQL and restart MySQL server)
# /etc/init.d/mysql stop
# mysqld_safe --skip-grant-tables &
# mysql -u root
mysql> use mysql;
mysql> update user set password=PASSWORD("newrootpassword") where User='root';
mysql> flush privileges;
mysql> quit
# /etc/init.d/mysql stop
# /etc/init.d/mysql start

Set a root password if there is on root password
# mysqladmin -u root password newpassword
Update a root password
# mysqladmin -u root -p oldpassword newpassword
Allow the user “bob” to connect to the server from localhost using the password “passwd” (login as root, switch to the MySQL db, give privs, update privs)
# mysql -u root -p
mysql> use mysql;
mysql> grant usage on *.* to bob@localhost identified by 'passwd';
mysql> flush privileges;

Give a user privileges for a database (login as root, switch to the MySQL db, grant privs, update privs)
# mysql -u root -p
mysql> use mysql;
mysql> INSERT INTO db (Host,Db,User,Select_priv,Insert_priv,Update_priv,Delete_priv,Create_priv,Drop_priv) VALUES ('%','databasename','username','Y','Y','Y','Y','Y','N');
mysql> flush privileges;

or
mysql> grant all privileges on databasename.* to username@localhost;
mysql> flush privileges;

To update info already in a table
mysql> UPDATE [table name] SET Select_priv = 'Y',Insert_priv = 'Y',Update_priv = 'Y' where [field name] = 'user';
Delete a row(s) from a table
mysql> DELETE from [table name] where [field name] = 'whatever';
Update database permissions/privileges
mysql> flush privileges;
Delete a column
mysql> alter table [table name] drop column [column name];
Add a new column to db
mysql> alter table [table name] add column [new column name] varchar (20);
Change column name
mysql> alter table [table name] change [old column name] [new column name] varchar (50);
Make a unique column so you get no dupes
mysql> alter table [table name] add unique ([column name]);
Make a column bigger
mysql> alter table [table name] modify [column name] VARCHAR(3);
Delete unique from table
mysql> alter table [table name] drop index [colmn name];
Load a CSV file into a table
mysql> LOAD DATA INFILE '/tmp/filename.csv' replace INTO TABLE [table name] FIELDS TERMINATED BY ',' LINES TERMINATED BY '\n' (field1,field2,field3);
Dump all databases for backup. Backup file is sql commands to recreate all db’s
# [mysql dir]/bin/mysqldump -u root -ppassword --opt >/tmp/alldatabases.sql
Dump one database for backup
# [mysql dir]/bin/mysqldump -u username -ppassword --databases databasename >/tmp/databasename.sql
Dump a table from a database
# [mysql dir]/bin/mysqldump -c -u username -ppassword databasename tablename > /tmp/databasename.tablename.sql
Restore database (or database table) from backup
# [mysql dir]/bin/mysql -u username -ppassword databasename < /tmp/databasename.sql
Create Table Example 1
mysql> CREATE TABLE [table name] (firstname VARCHAR(20), middleinitial VARCHAR(3), lastname VARCHAR(35),suffix VARCHAR(3),officeid VARCHAR(10),userid VARCHAR(15),username VARCHAR(8),email VARCHAR(35),phone VARCHAR(25), groups VARCHAR(15),datestamp DATE,timestamp time,pgpemail VARCHAR(255));
Create Table Example 2
mysql> create table [table name] (personid int(50) not null auto_increment primary key,firstname varchar(35),middlename varchar(50),lastnamevarchar(50) default 'bato');

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