A.PRIMARY KEY B.CHECK C.UNIQUE D.FOREIGN KEY
A.Int A[] B.String S[5] C.Int N[2 to 8, 3 to 6] D.Real R[6 to 3]
A.數(shù)據(jù)結(jié)構(gòu) B.數(shù)據(jù)約束 C.數(shù)據(jù)檢索 D.數(shù)據(jù)更新