w3schools is very useful for anything related to web design. They show how to use most of the basic functions you would need for any SQL database server. I also use phpmyadmin and its very good. it depends on what you want to change but it shouldn't effect your website to much for must things you would want to do. Unless you drop a table :\.

Hi Kushai,

How do you want to modify your database?. Do you mean upgrade or change the schema, or do you mean change the database type??

Most RPM based upgrades are pretty quick. what is the traffic like to your site. could it suffer a 'blip'?

If you mean upgrade whilst running your mileage may vary using several different approaches, what is the main balance of traffic to your site, is it more reads or writes? Can your site function in a read only manner for a small period of time?:

you could create a readonly MySQL replica (slave) on the same server using mysqld_multi(or do a dual install of MySQL). present the slave port to your web frontend.

Do the upgrade on your original MySQL server in the meantime. Drop the replica and repoint your webserver at the original MySQL port.

I've done this in several installations where appropriate and its worked great!

Another thing you could look into is caching the main pages to your site.