A.存儲(chǔ)問(wèn)題 B.共享問(wèn)題 C.安全問(wèn)題 D.保護(hù)問(wèn)題
A.2NF B.3NF C.4NF D.BCNF
A.數(shù)據(jù)定義 B.數(shù)據(jù)查詢 C.數(shù)據(jù)操縱 D.數(shù)據(jù)控制