is a phd important to find a good job after?

Depends on the job.
Some industries consider a PhD "career suicide". But if you want to be a uni lecturer it is pretty useful

It is strange, because it seems that you need the phd for "that specific job", but, it has been a waste of time when you got it...

can you explain gould? It might be me, but what you say doesn't make any sense

Yes, sure: looking for a job is strange activity because if you have a phd then you are too qualified, but if you don't have it, you have not specialized enough.

opens some doors and closes others.
Do a phd if you enjoy research - the rest will happen.

good answer...thank you

Depends very much on your field. For instance, their very useful for careers in the pure sciences, whilst in alot of other fields they don't improve your employability (or wages) at all.

Alot of people say that getting an UG degree improves your wage prospects (and employability) , but if you go on and do a PhD your wage prospects may well fall. At the end of the day, remember that a PhD is a training exercise designed for a career in academia.

this is a very interesting and useful thread- all the points made are excellent, I have never thought about it that way.