SQL中循环的基于集合的替代方法

Question

我读过许多帖子，在SQL中你应该考虑集合，而不是循环。我正在尝试执行以下操作：

SELECT SUM(Score)
FROM (SELECT W.StemId, W.Weight*Q.Weight As Score
    FROM TfidfWeights AS W
    INNER JOIN Query AS Q ON W.StemId = Q.StemId
    WHERE W.DocumentId = '0054f88e-a565-4f54-866a-e6107948567e') TMP

如何获得＆＃39;得分＆＃39;对于每个＆＃39; DocumentId＆＃39;我有。换句话说，避免循环通过＆＃39;文件＆＃39;表并计算得分＆＃39;对于每个文件。

Answer 1

获取每个DocumentID的总和

SELECT W.DocumentId, SUM(W.Weight*Q.Weight) As Score
FROM TfidfWeights AS W
INNER JOIN Query AS Q ON W.StemId = Q.StemId
GROUP BY W.DocumentId