This sounds like a job for awk.
You will most likely need to write your own script for your specific needs, but this site has some dialogue about how to go about doing this.
You could also use the cut utility to strip the fields out.
Something like:
cut -f 2,5,6 -d , filename
where the -f argument is the field you want and -d is the delimeter you want. You could then sort these results, find the unique ones, or use any other bash utility. There is a cool video here about working with CSV files from the command line. Only about a minute, I'd take a look.
However, I guess you could group the cut utility with awk and not want to use it. I don't really know what exactly you mean by native bash command though, so I'll still suggest it.