给需要学习的人,或者需要参加考试的朋友!Adatabasesystemgivesusawayof__A__togetherspecificpiecesorlistsof__B__thatarerelevanttousinourjobsorourlives.Italsoprovidesawayto__C__andmaintainthatinformationinacentralplace.Thefirstcommercialcomputerswerereally__D__morethandedicateddatabasemachineusedtoga