LINQ平均时间跨度？ [英] LINQ Average TimeSpan?

问题描述

我有一个包含了开始时间和事件的结束时间条目的数据库表。我想借这些条目，并查找事件的平均长度。减法是没有问题的。然而，当我试图让平均值，编译器会抱怨

I have a database table that contains entries for start time and end time of an event. I would like to take those entries and find the average length of an event. The subtraction is no problem. However, when I try to get the average value, the compiler complains.

下面是我当前的LINQ查询：

Here is my current LINQ query:

public TimeSpan? getAverageTime()
    {
        return (from EventTime in db.EventTimes
                where EventTime.EventTimesID > 0
                select (EventTime.TimeEnd - EventTime.TimeStart)).Average();
    }

我也试过.SUM（）和.Aggregate（），这样我可以有一些帮助，但没有被接受。

I also tried .Sum() and .Aggregate() so that I could have something to work with, but none are accepted.

什么是实现我目标的最佳方法是什么？

What is the best method for accomplishing my goal?

推荐答案

看来你必须使用LINQ2SQL语句SqlMethods.DateDiff（DATEDIFF函数如果SQL）：

It seems that you have to use a SqlMethods.DateDiff in linq2sql statement (DATEDIFF function if SQL):

public int getAverageTime()
    {
        return (from EventTime in db.EventTimes
                where EventTime.EventTimesID > 0
                select (SqlMethods.DateDiffMinute(EventTime.TimeStart, EventTime.TimeEnd)).Average();
    }

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