历届中级程序员的经典题集，给需要学习的朋友们

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