List matching values

I'm fairly certain I have seen this somewhere before, but I can't find the formula now. I have a spreadsheet of names, id numbers and other info; I want to create a list to show matching info, for instance, three people have a code of a###, and three have a code of b###, but I know that there will never be more than 40 people with any letter suffix of the code. Is there a formula that I can copy down 40 rows to list out the A*, then change it to list out 40 rows of B*?