my old sink had a over flow hole in it and the new sink does not.can i still use the same drain pipe or is there a different type that i need to get?
You're in good shape- the overflow was internal. The same drain is all you need.
Assuming you mean the pop up drain (chrome), I suggest you dry fit the old one into the new sink. Often, the pop ups for internal overflow sinks have a large opening allowing water from the overflow into them. It may not seal on the new sink depending on the thickness of the new sink. If it doesn't seal, not the end of the world. Visit a good local plumbing supply store and ask for a pop up drain for a sink with no overflow.
