query to concatenate columns if record duplicate

My table has two column that is id and name. I want to do concatenate the columns if the if more than two names are same like: id name 1 John 2 David 3 Zed 4 John 5 David 6 John 7 David 8 John 9 John Now I want my output that if name is repeated than the first record will remain as it is and other will be concatenated by id like Id Name 1 John 2 David 3 Zed 4 4 John 5 5 David 6 6 John 7 7 David 8 8 John 9 9 John Can anyone please help...Thank you