Trying to transpose values from various rows to a cell

Hi Guys, Desparetly need help with this task. Can someone please help?

I have a spreadsheet with over 4000 rows of data. The spreadsheet has course codes, course dates (this information is split into three separate fields called; day, month and year). On top of that I have inserted 12 blank columns (one for each month). Essentially I need to consolidate dates; based on course codes and months. e.g. all the January dates for the first course code need to be concatenated (separated by a comma) into the Jan column in the first row for that course code. Each code has anywhere between 10-15 rows. Please see the attached spreadsheet for an example.

Thanks in advance.