solution 1

CREATE TABLE student
(
    rollno NUMBER  primary key,
    name VARCHAR(20) NOT NULL,
    class VARCHAR(20) CHECK(class IN('fybca','sybca','tybca','graduate')),
    result VARCHAR(20) CHECK(result IN('pass','faile','status'))
);
CREATE TABLE Result
(
    rollno NUMBER,
    m_sub1 NUMBER CHECK(m_sub1>=0 AND m_sub1<=100),
    m_sub2 NUMBER CHECK(m_sub2>=0 AND m_sub2<=100),
    m_sub3 NUMBER CHECK(m_sub3>=0 AND m_sub3<=100),
    foreign key(rollno) references student(rollno) ON DELETE cascade
);

--sequence
CREATE sequence s1
increment BY 1
START WITH 1
minvalue 1
maxvalue 200
ORDER;

--insertion
INSERT INTO student VALUES(s1.NEXTVAL,'Aniket','sybca','status');
INSERT INTO student VALUES(s1.NEXTVAL,'Aadesh','fybca','status');
INSERT INTO student VALUES(s1.NEXTVAL,'Darshan','tybca','status');
INSERT INTO student VALUES(s1.NEXTVAL,'Ankit','sybca','status');
INSERT INTO student VALUES(s1.NEXTVAL,'Dhruv','fybca','status');





CREATE OR REPLACE TRIGGER t1
after INSERT OR UPDATE ON result
FOR each ROW
DECLARE
c VARCHAR(10);
CURSOR c1
    IS SELECT class
    FROM student
    WHERE rollno=:NEW.rollno;

BEGIN

    IF inserting THEN
        IF(:NEW.m_sub1<33 OR :NEW.m_sub2<33 OR :NEW.m_sub3<33 ) THEN
            UPDATE student
            SET result='faile'
            WHERE rollno=:NEW.rollno;
        ELSE

            UPDATE student
            SET result='pass'
            WHERE rollno=:NEW.rollno;
            OPEN c1;
            FETCH c1 INTO c;

            IF(c='fybca') THEN
                UPDATE student
                SET class='sybca'
                WHERE rollno=:NEW.rollno;
            ELSIF(c='sybca') THEN
                UPDATE student
                SET class='tybca'
                WHERE rollno=:NEW.rollno;
            ELSIF(c='tybca') THEN
                UPDATE student
                SET class='graduated'
                WHERE rollno=:NEW.rollno;
            END IF;
            CLOSE c1;
        END IF;

    END IF;
END t1;
/


--insertion result
INSERT INTO Result VALUES(21,35,46,87);
INSERT INTO Result VALUES(22,98,87,65);
INSERT INTO Result VALUES(23,98,87,65);
INSERT INTO Result VALUES(24,47,76,66);
INSERT INTO Result VALUES(25,88,66,25);