MySQL: How to create a database

  To create a simple database (e.g. if you need to create one for a WordPress or Wiki install) use the following after logging in to MySQL as the root user:  
create database [nameOfDatabase];
  Don’t forget the ; at the end, or you’ll end up on a new line consisting of a > prompt waiting for more input. You can put the ; in then if you forgot to complete the command. An example of the above would be:  
create database wikiDB;
  …which would create the database named wikiDB. You should see the following on a successful command:
  Query OK, 1 row affected (0.04 sec)
          If that is all you had to do you can now exit MySQL by typing:  
exit
  …and you’re done!

How To: Export all mysql databases for backup

This is a handy command for anyone using multiple mysql databases – it produces a single file which you can easily back up to elsewhere.  
mysqldump -u root -p –all-databases > databasesBackup.sql
  Note the two hyphens before “all”. This command creates the file databasesBackup.sql which contains the contents of all of your databases. This file can be easily rsync’d or scp’d elsewhere to create an offsite backup of your site’s databases.