Question

我有以下疑问，我希望找到一个更好的方法来做到这一点，因为它看起来不像我这样做...

修改

对不起，我没有说明我只想返回实际符合所有设施的广告！

SELECT TOP 50 Advert.Id
FROM Advert 
WHERE Id in(SELECT Advert_id FROM AdvertsToAmenities WHERE Amenity_id = 1   AND Advert_Id = Id)
  AND Id in(SELECT Advert_id FROM AdvertsToAmenities WHERE Amenity_id = 3   AND Advert_Id = Id)
  AND Id in(SELECT Advert_id FROM AdvertsToAmenities WHERE Amenity_id = 5   AND Advert_Id = Id)  

-- OR --

SELECT TOP 50 Advert.Id
FROM Advert 
JOIN AdvertsToAmenities a on Advert.Id = a.Advert_id
JOIN AdvertsToAmenities b on Advert.Id = b.Advert_id
JOIN AdvertsToAmenities c on Advert.Id = c.Advert_id
WHERE a.Amenity_id = 1 
  AND b.Amenity_id = 3 
  AND c.Amenity_id = 5

我很想知道如何优化这些查询！

Answer 1

您的查询对我来说很好。另一种选择是使用这样的东西：

SELECT TOP 50 Advert.Id
  FROM Advert JOIN AdvertsToAmenities a ON Advert.Id = a.Advert_id
 WHERE a.Amenity_id = 1 
    OR a.Amenity_id = 3 
    OR a.Amenity_id = 5
 GROUP BY Advert.Id
HAVING COUNT(DISTINCT a.Amenity_id) = 3

如果(Advert_Id, Amenity_id)对是唯一的，您可以放弃DISTINCT。

Answer 2

您的查询的以下重组如何，您只需创建一个逗号分隔的特定礼仪ID列表？

SELECT TOP 50 
a.[ID]
FROM [Advert] a
INNER JOIN 
(
    SELECT ata.[Advert_ID]
    FROM [AdvertsToAmenities] ata
    WHERE ata.[Amenity_ID] 
    IN (1, 3, 4, 5) -- Your list of amenity IDs
) as ata
ON a.[ID] = ata.[Advert_ID]

这使用动态表语句预先过滤那些适用的设施，然后再加入广告列表。注意，Sql Server将在执行前大量优化子查询。这应该意味着您将从Sql Server提供的所有优化中获得更易于维护的语句的好处。

Answer 3

*试试这个简单的

SELECT TOP 50 a.Id
FROM Advert a, AdvertsToAmenities b 
WHERE a.Amenity_id in ('1','3','5')
and a.Id = b.Amenity_id

SQL Server查询优化问题

3 个答案: