Difference between revisions of "MySQL"

Revision as of 17:30, 6 January 2012

Can I use MySQL on your server?

Yes, if you have a "Starter Virtual Host" or above. Please note that MySQL is not enabled for "Simple Virtual Host" accounts. A list of features for each account type is available here. If you need this feature, please email support@he.net to request an upgrade of account type.

How do I access my database?

Your Account Database is already initialized by default and ready for your use.

New accounts (on our version 3 servers) come with PHPMyAdmin, a web-based MySQL management tool. Simply open http://mydomainname.com/phpmyadmin in your browser and log in with your account name and database password.

You can also manage your database via SSH. After logging in with ssh, type: mysql -p . It will prompt you for the database password.

You can also access it with the following commands:

     mysql -u my_user_name --password=my_password
     mysql -u my_user_name -p 

Your User Name and Database Name are both the same as your HE account name.

How do I change my mySQL password?

You can set your MySQL password in http://admin.he.net. Log into your account and click on "Issue New Password". Re-enter your admin password in the "Password" field (unless you want to change it, too), and enter your new MySQL password in the "MySQL Password" field.

Alternatively, you can change your password from within MySQL (if you know your current one). First, log in to your mySQL database from a shell prompt. Then issue the following command:

set password=password('new_password');

where new_password is the new password you have selected.

Example

set password=password('charlie1');

What is the mysql port number?

The port is the default standard port: 3306. Most programs like PHP and Perl DBI will take this port if it is not specified.

How do I backup or transfer my database?

mySQL databases are not backed up like ordinary files. Even if it were possible, it would not be a good solution, as it could corrupt the database by doing so.

To back up your database using PHPMyAdmin, log in, select your database, and use the "Export" tab. Keep all the tables and the "SQL" format selected and click on "Go" in the lower right. To restore the backup, use the "Import" tab.

Backing up and restoring your database using SSH is a bit more complicated. Once logged in, use the mysqldump command:

     mysqldump -ppassword DatabaseName > db.sql 

('db.sql' is the name of your backup dump file, which you can change to whatever name you choose)

That backs up the whole database in standard SQL text format. Both the structure (like CREATE table command) and data (like INSERT command) statements, can be backed up separately, which is usefull in many cases. Check:

     mysqldump --help

for all the command line options.

To restore the dump, just type:

     mysql -p dbname < db.sql

Note that the structure dump won't work if tables already exist. The backup will not change or replace the structure.

For the data dump (the INSERT commands) it will append any new data if it does not yet exist.

If you have a database that is in frequent use, such as one linked to a dynamic web interface being updated by your web site visitors, it is a good idea to make a daily backup of the data.

To transfer a database, create the dump as described above, use ftp to upload it on the second server, and then restore it as above.

Backing up the database is not done through an ftp database directly. You first need to generate an sql dump, and then download this dump.

Use the following mysqldump command:

     mysqldump -ppassword username > somefile.sql 

Then use the following command to view the dump:

     view somefile.sql 

(exit with: q!)

To put the file back:

• upload the file
• edit it with a text editor, adding the below line to the top:

     use databasename (which is the same as your username)

• save the file and issue the command:

     mysql -ppasswd < somefile.sql 

All of the database will be generated, including structure. For more details, use

     mysqldump --help