part3.txt

来自「ssd7的练习1」· 文本 代码 · 共 16 行

1. Result of the set difference operation s - r:
A B C 
b g a

( 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'
);
2.The above statement  returns a list of member numbers of the members only borrowing the book that has the call number QA76.9.D26C66 but not borrowing the book that has the call number QA76.9.D7E53.