試題詳解

8设有关系模式SCSno, Sname, Sex, Birthday, Cno, Cname, Grade, Tno, Tname满足函数 依赖集：{Sno→Sname, Sno→Sex, Sno→Birthday, Cno→Cname, Sno, Cno→Grade, Tno→Tname}.SC的主码和属性集Sno, Tno的闭包分别是
(A)Sno,Tno和{Cno,Cname,Grade,Tno,Tname}
(B)Sno, Cno, Tno和{Sno, Sname, Sex, Birthday, Cno}
(C)Sno, Cno和{Sno, Sname, Sex, Birthday, Cno, Cname, Grade}
(D)Sno, Cno, Tno和{Sno, Sname, Sex, Birthday, Tno, Tname}