How important are constraints like NOT NULL and FOREIGN KEY if I'll always control my database input with PHP?

Question

I am trying to create a column in a table that\'s a foreign key, but in MySQL that\'s more difficult than it should be. It would require me to go back and make certain changes

Answer 1

You can't "just" do it with PHP for the same reason that programmers "just" can't write bug-free code. It's harder than you think. Especially if you think it's not that hard.