A.UNIQUE B.COUNT C.DISDINCT D.UNION
A.數(shù)據(jù)庫(kù)實(shí)施 B.邏輯結(jié)構(gòu)設(shè)計(jì) C.概念結(jié)構(gòu)設(shè)計(jì) D.數(shù)據(jù)庫(kù)運(yùn)行和維護(hù)
A.數(shù)據(jù)冗余 B.數(shù)據(jù)被非法讀取 C.數(shù)據(jù)被非法修改 D.發(fā)生死鎖