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Consider a relation of scheme Building(Street, Number, No.Apartments, Color, Age).
TRC: find the oldest building in Downing Street.
相關的SQL語句應該是:
SELECT MAX(Age) AS ‘Oldest building’, Street FROM Building WHERE Street = ‘Downing Street’;
使用TRC我的答案:(B代表建立關係)
{V.*|V(B) | V.BAge >=Age^V.Bstreet = ‘Downing Street’}
V.*
(它返回埃夫裏單建築物元組)
V(B)
(它映射變量V至建築物的元組)
V.BAge >=Age^V.Bstreet = ‘Downing Street’
(這裏我設置的條件...也許..)
下面的答案有幫助嗎?如果是這樣,你應該接受它作爲答案。 –