Change a list of items bought to a list of purchasers and what they bought

Hello all,

Here is what I have:
Table 1.PNG

Here is what I want:
Table 2.PNG

This, of course, is a representation. It is actually thousands of IDs and items. I know to get the list of purchasers, I copy the ID column and remove duplicates. How do I then get the items purchased in that format?

Thanks in advance!