A
CREATE VIEW v1 SELECT s#,sname,sex,cname,teacher,grade FROM S,SC,C WHERE S.s#=SC.s# AND SC.c#=C.c# AND c#='c2'
B
CREATE VIEW v1 AS SELECT s#,sname,sex,cname,teacher,grade FROM S,SC,C WHERE c#='c2'
C
CREATE VIEW v1 AS SELECT s#,sname,sex,cname,teacher,grade FROM S,SC,C WHERE S.s#=SC.s# AND SC.c#=C.c# AND c#='c2'
D
CREATE VIEW v1 AS SELECT s#,sname,sex,cname,teacher,grade FROM S,SC,C WHERE S.s#=SC.s# AND c#='c2'