A.BD B.BCD C.BC D.CD
A.1NF B.2NF C.3NF D.BCNF
A.未回退的數(shù)據(jù) B.未提交的數(shù)據(jù) C.回退的數(shù)據(jù) D.未提交隨后又被撤消的數(shù)據(jù)