Post method/Database

Question

I'm studying the html/css book by John duckett. Says in the book that the post method should be used if: the form is very long, users can upload files, if there is sensitive data such as passwords, or if users can add or delete info from a database(I dont understand this either, could someone please also explain what a database is and how users can interact with it). Now, with that being said, there is an example in the book of a user being able to submit their departure date, and the method=post....???Why????? Is this an example of data being added to the database? Because if it's not, I dont understand what it's being used in this example for. Out of all the things I just listed above, adding info to the database is the only one I see that would validate making this a post method, and not get. And once again, could someone please explain to me what the heck a database is and how it works?

Answer 1

A database is usually just a collection of tables with a querry interface(usually sql)
But you'll need php(or any other backend code) that converts user input into sql querrys.
But be aware of sql Injektion

Answer 2

An easy order of languages for you to learn is html>css>js>sql>php