Which to use, concat, concat_ws? in mysql

I need to change this data

FirstName | MiddleName | LastName
---------------------------------
Robert    | Thomas     | Smith

Into the string "Smith, Robert Thomas"

I'm not sure if I need to use a join, concat or concat_ws.

I know that if I use

concat_ws(', ',LastName,FirstName,MiddleName)

Then I get "Smith, Robert, Thomas" but i need "Smith, Robert Thomas".

Any advice?