Wednesday, December 11, 2013

MySQL commands

As root, create a database and grant permissions to a new user

To connect to the mysql client as root
mysql -u root -p
You'll be prompted for the password.

How to create a new user
CREATE USER 'newuser'@'localhost' IDENTIFIED BY 'password';
Create a database
create database databasename
Connect to a database
connect databasename
 Grant permissions to a user
GRANT ALL PRIVILEGES ON * . * TO 'newuser'@'localhost';
Then you can log out of mysql

As a user 

To connect to the mysql client as a user
mysql -u username -p
If you have the correct privileges, you can also create a database with a pipe. How to create a database
echo "create database databasename" | mysql -u username -p
Load a dump
cat file.sql | mysql -u username -p databasename

Graphical client

On Ubuntu, I used mysql navigator by shi bok jang.
On Debian, I used  mysql workbench

More on users

Change password, as the user itself or as root:
SET PASSWORD FOR 'Karl'@'localhost' = PASSWORD('cleartext password');
As root , list all users
SELECT User FROM mysql.user;
As root , delete a user
drop user Rasdfas@localhost;
MySQL documentation on adding user accounts.

More on databases

Commands below work if your shell user name is the same as your mysql user name. If it's dufferent add -u username to the command.

List all databases (in mysql client)
show databases
Delete a database (in the mysql client)
DROP database databasename;
Rename a database  (in the shell)
mysqladmin -p create new_database
mysqldump -p old_database | mysql -p new_database
After you have verified that everything is in order
drop database old_database
Move a table from one database to another
mysqldump -p database_1 table_name | mysql -p database_2 
Back up only part of a database with the where option
mysqldump -p -w"productcode=440799" tradeflows raw_flow_yearly > sawnwood99raw.sql
Back up only the structure of a database (not the data)
mysqldump -p -d tradeflows > tradeflows.sql
Load a dump into a database :
cat file.sql | mysql -u username -p databasename

Configuration file my.cnf

It's not desirable to share user name and password in software disseminated over the internet. User name, password and database names can be placed under groups in the configuration file. For example for a given project enter this group in ~/.my.cnf
user = user
password = password
host = localhost
database = dbname
Then simply specify group=project_name to the client that accesses the database.

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