I read a DBF file (with more than 1.000.000 records) into a datatable.
I can read that data, but now I want to group by on 2 columns (sampnumber,testcode)
Once I know the unique records by (sampnumber,testcode), I want the last 29 records for every sampnumber,testcode in the data.
I've been looking for the solution, but I just can't find it.
The columns I have:
sampnumber, sampname, samplenr, date, testcode, testname, result, unit