使用计数从 GAE 数据存储查询
目前，我从数据存储中获得 Android 应用程序的最高分，如下所示：
Query query = pm.newQuery(PlayerPersistentData.class);
query.setOrdering("rating desc");
query.setRange(0, 25);
但是，我还想按辅助列的计数对结果进行排序：
例如，在普通 SQL 中，它会是这样的：
select PlayerPersistentData.*, count(achievements) as achievements_count
from PlayerPersistentData
order by rating desc, achievements_count desc
成就是在数据存储中定义如下
@Persistent
private Set<Integer> achievements;
这可以使用 GAE 数据存储吗？如果是这样，我应该如何创建我的查询？
提前致谢
At the moment I am getting the top scores for my Android application from the datastore as follows:
Query query = pm.newQuery(PlayerPersistentData.class);
query.setOrdering("rating desc");
query.setRange(0, 25);
However, I would also like to order the results by the count of a secondary column:
E.g. In normal SQL it would be something like this:
select PlayerPersistentData.*, count(achievements) as achievements_count
from PlayerPersistentData
order by rating desc, achievements_count desc
Achievements is defined in the datastore as follows
@Persistent
private Set<Integer> achievements;
Is this possible using the GAE datastore? And if so how should I create my query?
Thanks in advance
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您可以使用 addSort 方法到您的 Query 对象，如下所示：
You can use the method addSort to your Query object like this:
您需要非规范化：将计数存储为实体上的单独字段，然后对其进行查询。
You need to denormalize: store the count as a separate field on your entity, and query on that.