Create Table EXAMS ( SUB_NO integer Not Null, STUDENT_NO integer Not Null, MARK decimal (3), DATE_TAKEN date Not Null, Primary Key (SUB_NO, STUDENT_NO, DATE_TAKEN));
The above SQL statement is used to create the EXAMS table. Considering the EXAMS table; which of the following table contents can't be inserted to the EXAMS table (assume date format is correct)?
a. alter table exams add student no as foreign key (exams); b. alter table exams add foreign key (student no) references students; c. alter table sub no add foreign key (exams); d. alter table exams foreign key (sub no);