If anyone feel interested after reading this comment, checkout the book called "Developing Time-Oriented Database Applications in SQL".

edit: it contains many database-patterns that are useful even you aren't building time-oriented applications. It will make you a better developer.

edit 2: basically, once you know some things from this book, every time you encounter a new database engine or programming language, the first thing you will want to look at is how the language handles dates & times - suddenly this kind of field become way more interesting. So the book might change how you view dates/times permanently, just be careful if you tend to over-engineer or are perfectionist, because it makes it easy to do so. Apply the patterns when it makes pragmatic sense.