This is a list of what I have learned from my experience in the past, and I hope I do not make the same mistake in the future.
If you an Analyst,
Do make a good documentation before development.
A good documentation can make a fast development.
A good documentation can make track every change while in development.
A good documentation can make a programmer know about a problem with means they will know which algorithm or logic is the best that they will applied to the problem.
If you a DBA,
Do not change a field name in table occasionally.
Changes in fields name impact to programmer time, and most programmer does not like it.
If you really need to change a field name, make a new field but do not delete the old one, mark them as an absolute.
Trigger is fast but trigger can make you triggered in the late of the night after it.
Believe me with this one, Oracle suck! do not use it.
If you are a Programmer,
Do read and learn. Don't wasting others team with your stupid question, what you must do is: Googling.
Then ask your friend, if you cannot solve the problem.
Algorithm is cheap, time was expensive! Make or use a fastest algorithm as possible!
Comment your code, please.