我有一个使用 Linq 从数据库中获取数据的函数,然后我在另一个函数中调用该函数以对每个单独的属性使用 .Sum 来对所有单独的属性求和。我想知道是否有一种有效的方法可以一次对所有属性求和,而不是在每个单独的属性上调用 .Sum() 。我认为我现在做的方式非常慢(尽管未经测试)。
public OminitureStats GetAvgOmnitureData(int? fnsId, int dateRange)
{
IQueryable<OminitureStats> query = GetOmnitureDataAsQueryable(fnsId, dateRange);
int pageViews = query.Sum(q => q.PageViews);
int monthlyUniqueVisitors = query.Sum(q => q.MonthlyUniqueVisitors);
int visits = query.Sum(q => q.Visits);
double pagesPerVisit = (double)query.Sum(q => q.PagesPerVisit);
double bounceRate = (double)query.Sum(q => q.BounceRate);
return new OminitureStats(pageViews, monthlyUniqueVisitors, visits, bounceRate, pagesPerVisit);
}
编辑
private IQueryable<OminitureStats> GetOmnitureDataAsQueryable(int? fnsId, int dateRange)
{
var yesterday = DateTime.Today.AddDays(-1);
var nDays = yesterday.AddDays(-dateRange);
if (fnsId.HasValue)
{
IQueryable<OminitureStats> query = from o in lhDB.omniture_stats
where o.fns_id == fnsId
&& o.date <= yesterday
&& o.date > nDays
select new OminitureStats (
o.page_views.GetValueOrDefault(),
o.monthly_unique.GetValueOrDefault(),
o.visits.GetValueOrDefault(),
(double)o.bounce_rate.GetValueOrDefault()
);
return query;
}
return null;
}
编辑:
public class OminitureStats
{
public OminitureStats(int PageViews, int MonthlyUniqueVisitors, int Visits, double BounceRate)
{
this.PageViews = PageViews;
this.MonthlyUniqueVisitors = MonthlyUniqueVisitors;
this.Visits = Visits;
this.BounceRate = BounceRate;
this.PagesPerVisit = Math.Round((double)(PageViews / Visits), 1);
}
public OminitureStats(int PageViews, int MonthlyUniqueVisitors, int Visits, double BounceRate, double PagesPerVisit)
{
this.PageViews = PageViews;
this.MonthlyUniqueVisitors = MonthlyUniqueVisitors;
this.Visits = Visits;
this.BounceRate = BounceRate;
this.PagesPerVisit = PagesPerVisit;
}
public int PageViews { get; set; }
public int MonthlyUniqueVisitors { get; set; }
public int Visits { get; set; }
public double PagesPerVisit { get; set; }
public double BounceRate { get; set; }
}
最佳答案
IIRC 你可以用
一次完成所有的总和(只要查询被翻译成SQL)var sums = query.GroupBy(q => 1)
.Select(g => new
{
PageViews = g.Sum(q => q.PageViews),
Visits = g.Sum(q => q.Visits),
// etc etc
})
.Single();
这将为您提供一个对象,其中包含作为单独属性的所有总和。
关于c# - 在多个属性上调用 .Sum() 的有效方法,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/11335418/