This answer assumes that your csv file has one line per row, meaning that there are no continued lines. If the file is called db.csv, then you can get 10 lines, including the first and the last by using:
awk 'FNR==NR{next} FNR==1{incr=(NR-1)/9} FNR>x{x+=incr;print} END{print}' db.csv db.csv