While you are encouraged to use the Internet to help you learn PHP, you cannot simply copy and paste full pages of code (i.e. from db connection to manipulation to feedback messages) and present it as yours. Yes, it is difficult to know what constitutes plagiarism, but when a student submits code that includes advanced functions as if they coded it, even with original comments from the originator included, then it becomes very obvious. I can immediately pick up when you have coded something that you could not have mastered in three months. And then this code gets distributed between fellow students, who simply change a few variable names and present it as if they coded it.
Do not even attempt it. The new submission procedure allows me easier access to your code (the name of your zip file/uploaded to Osprey/the way I can easily unzip all submissions with one click etc.). I have powerful code search software that quickly highlights code/logic that is the same. You cannot hide it, so don't do it.