使用LINQ获得平均值 [英] Get Average Using LINQ
问题描述
希望有人可以帮助我使用LINQ语法来计算平均值.例如,我有以下LINQ查询:
Hoping someone can help me with the LINQ syntax to calculate an average. For example, I have the following LINQ query:
var rates = from rating in ctx.Rates
where rating.Id == Id
select new
{
UserId = rating.UserId,
Rating = rating.Rating
};
如果返回10条记录,则需要在评分"字段上计算平均值.在我的数据库中,它被定义为Double.我正在使用LINQ to EF.因此,我将分配UserId,MiscId,并且Rating将是返回记录的平均值.我正在将一个对象传递回客户端代码.
If 10 records are returned, I need to calculate average on the Rating field. It is defined as as a Double in my DB. I am using LINQ to EF. So I would be assigning the UserId, MiscId, and the Rating would be the average on the records returned. I am passing one object back to the client code.
推荐答案
您要查找每个用户ID的平均评分吗?如果是这样,则您需要同时使用 GroupBy 和
Are you looking for an average rating per user id? If so, then you need to use both GroupBy and Average.
var rates = ctx.Rates
.Where( r => r.Id == Id )
.GroupBy( g => g.UserId, r => r.Rating )
.Select( g => new
{
UserId = g.Key,
Rating = g.Average()
});
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