Database design

I will confess to knowing next to nothing about database design, but the concept interested me. Whenever I have to make a telephone call or send an email to my bank or mobile phone company I wonder what information they hold.

If I were to design the system, I would break the information down as follows:

Standing info e.g. name, address, date of birth

Event data (for each phone call/email) e.g. person it relates to, staff member, date, time, what standing info changed [automatic], notes, files e.g. recording of telephone calls, copies of emails, scanned in correspondence

Actions e.g. instructions of what to do, status

I also wonder how many government databases are there? How many times is my name and address recorded. Is it possible to consolidate this information? Would it be possible to have different functional departments with access to different information? e.g. doctors can't find out about points of driving licence, tax inspectors can't find out about education record, but both can see home address.