CREATE TABLE course
(
    cno VARCHAR2(10),
    credit  NUMBER(4)
);

CREATE TABLE SC
(
    sno VARCHAR2(10),
    cno VARCHAR2(10),
    grade NUMBER(4)
);

CREATE TABLE credit
(
    sno VARCHAR2(10),
    sumcredit NUMBER,
    notpass NUMBER
);

------解决方案--------------------
楼上已OK了!你看看!