Secure programming tip No. 2: Store what you need, and not one bit more
Before you ask for your customer's snail mail address, ask yourself whether you will ever send them a letter through the post office. If email is sufficient, you might want to rethink storing home or business addresses. That information costs time to process, takes up disk space, and makes an attractive target for information thieves.
Programmers often think like obsessive hoarders, storing away copies of anything that stands the least chance of someday being useful. This instinct may help debug software, but it leaves a trail of data for anyone to find.
Is every column and table in the database absolutely necessary? When in doubt, make the forms shorter and the database tables smaller. Avoid the temptation to be a data pack rat.