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Consider a relation of scheme Building(Street, Number, No.Apartments, Color, Age).
TRC: find the oldest building in Downing Street.
相关的SQL语句应该是:
SELECT MAX(Age) AS ‘Oldest building’, Street FROM Building WHERE Street = ‘Downing Street’;
使用TRC我的答案:(B代表建立关系)
{V.*|V(B) | V.BAge >=Age^V.Bstreet = ‘Downing Street’}
V.*
(它返回埃夫里单建筑物元组)
V(B)
(它映射变量V至建筑物的元组)
V.BAge >=Age^V.Bstreet = ‘Downing Street’
(这里我设置的条件...也许..)
下面的答案有帮助吗?如果是这样,你应该接受它作为答案。 –