part3.txt

来自「ssd7的本人的答案」· 文本 代码 · 共 20 行

1.
operation s - r.
D	E	F
b	g	a

2.
( SELECT   MemNo
  FROM     MEMBER, BOOK
  WHERE    MemNo = BorrowerMemNo AND
  CallNumber = 'QA76.9.D26C66'
)
EXCEPT
( SELECT   MemNo
FROM     MEMBER, BOOK
WHERE    MemNo = BorrowerMemNo AND
CallNumber = 'QA76.9.D7E53'
);

Returns a list of member numbers, they are from the members who borrow the book having call number QA76.9.D26C66 but not QA76.9.D7E53.