I have been out of the database design game for over three years, but a friend wants a address book designed for his Real Estate office. My question is I have a table called contact which has a foreign key to a address table, now I also have a company table (since he has three offices) which refer's the same address table in the same manner. Is that breaking the normalization rules or is there a better way to do it? I have looked high and low for a good example of a address schema, but can't find one. Any help would be much appreciated.