It seems that your subscriberID field in the saved_holidays table references the field email in your subscriber table.
This might be not a PHP problem: maybe you just violated a foreign key constraint. If you don't know about foreign key constraints, please, stop writing your application right now, and throughfully read the Wikipedia article I linked.
I cant really gove you an answer,but what I can give you is a way to a solution, that is you have to find the anglde that you relate to or peaks your interest. A good paper is one that people get drawn into because it reaches them ln some way.As for me WW11 to me, I think of the holocaust and the effect it had on the survivors, their families and those who stood by and did nothing until it was too late.