怎么写这个查询？ [英] How to write this query?

问题描述

我有一个名为 ProductLike（ProductId，UserId，Like）的表。每当用户喜欢某个产品时，就会在此表中添加一条记录，其中包含 UserId ， ProductId （该产品很受欢迎）和喜欢（真或假）。

我想从这里获得 usersId ProductLike 表喜欢一种产品的表。更确切地说，我希望得到一个列表或一组用户，他们对每种产品都喜欢相同的产品。



请指导如何编写查询。



我正在写这个，但它有错误：

Hi,
I have a table Named ProductLike(ProductId, UserId, Like). Whenever user likes a product then a record is added in this table with UserId, ProductId(which product is liked) and Like(true or false).
I would like to get such usersId from the ProductLike table who has liked one product. To be more precise, I want to get a list or group of users who has liked same product for each product.

Please guide How can I write a query.

I am writing this one but it has errors:

select p.UserId,* from ProductLike p where p.ProductId = (select pk.ProductId from ProductLike pk
where pk.ProductLike=1)

请指导，因为我的查询不是解决方案，只是提示。

Please guide as my query is not a solution it is just hint.

推荐答案

SELECT ProductId, UserId
FROM ProductLike
WHERE [Like] = 1
ORDER BY ProductId, UserId

如果你想要一份清单特定产品（例如 ProductId 1）添加

AND ProductId = 1

到 WHERE 子句。



请注意赞是保留关键字 [ ^ ]和你一起可能想为该字段使用另一个名称。

to the WHERE clause.

Please note that Like is a reserved keyword[^] and you might want to use another name for that field.

不确定我是否正确理解了这个问题，但你提到了组。因此，如果您需要每个产品以及有多少用户喜欢它，则查询可能类似于：

Not sure if I understood the question correctly, but you mentioned group. So if you need each product and how many users liked it, the query could be something like:

SELECT pl.ProductId,
       COUNT(*) AS NumberOfLikes
FROM   ProductLike pl
WHERE pl.[Like] = True
GROUP BY pl.ProductId

不确定我是否'你在问题中遗漏了一些东西，但我认为这样做会有所作为。你将获得一个包含部分所有产品的结果集。

Not sure if I''m missing somethin in your question, but I would think this would do the job. You''ll get a result set that contains all the products in sections.

SELECT ProductId, UserId
  FROM ProductLike
 WHERE Like = 1
 ORDER BY ProductId, UserId

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