First thing you need to understand is that PVC and ABS are not "glued" together. The products we commonly call "glue" are actually solvents that briefly melt the top surfaces of the pipe and fitting which then blend together when joined. This is a solvent welded joint. Since ABS and PVC are different materials chemically, they need different solvents. I have heard of a product that supposedly will work on both ABS and PVC thereby allowing the two materials to be joined, but I am not sure of how reliable it is. I would still use a banded coupling if I had to join ABS and PVC. Others may have a better read on this than I, but I would proceed cautiously.