security & forms

[Grant_Cooper]

I am building this outline database using sessions. And need some help. I'm looking for security flaws building forms using php and mysql using sessions. If anyone could recomend a book or a hyper link that woudl be great.

[Grant_Cooper]

Here's my problem.

I am using php to do error checking before I allow the user to input anydata. If they make an error I pass the primary key in the post as a hidden variable. But I can see someone playing with the header and causing havoc. I'm looking for some reading on this. Or a solution. Do I have to use sessions to encrypt the primary key?