MySQL is the database engine used in many WordPress sites. Understanding how databases work help you fix problems that can occur.
For example one time I helped a client who had installed a plugin and when they removed it they deleted some of the information in use in their site. I had to go back and restore the MySQL database table which held that information. Otherwise they would have had to reenter the information which is time consuming and prone to errors.
You don’t have to be an expert to fix MySQL problems. MySQL Admin is an easy to understand program that is often in the CPANEL or website tools for a website. There are many step by step guides on how to fix common problems with your SQL database. In addition your hosting provider can also assist you if you don’t feel comfortable doing this. It is easy to make a mistake, and you have to be thoughtful and careful doing this work.
When you delete plugins you have to really trust the authors and the quality of the plugin. I have had some bad experiences since I test many plugins and I have a strategy before and after I install a plugin. I look at the SQL tables in WP-Optimize (another plugin) and then I uninstall the plugin. Then I look again at WP-Optimize which lists all the tables. Most of the time it shows that all the tables were deleted properly. If there are still tables that need to be deleted that the uninstaller didn’t uninstall then I delete them.
Over time you will learn what the tables are in your database and to recognize what should be there and shouldn’t be there. It helps that WP-Optimize labels them with the plugins name if it knows. I have found this to be a great way to keep my database lean and mean. Otherwise the bigger your database becomes the slower it gets.
Good luck my budding SQL experts!