Question

我是在LINQ-to-SQL中编写查询，在此查询中是Date列。我想按“周”分组结果。我将如何在LINQ-to-SQL中执行此操作？

由于

Answer 1

假设格里高利历，“第一天”周规则，并且一周的第一天是星期一。

第一天的一周规则：

表示一年的第一周从第一天开始在下一个指定的第一天之前的年份和结束周

int firstDayOfWeek = (int)DayOfWeek.Monday;
var q = 
    from u in TblUsers
    let date = u.CreateDate.Value
    let num = date.DayOfYear - 1
    let num2 = ((int)date.DayOfWeek) - (num % 7)
    let num3 = ((num2 - firstDayOfWeek) + 14) % 7
    let week = (((num + num3) / 7) + 1)
    group u by week into g
    select new 
    {
        Week = g.Key,
        Count = g.Count ()
    };

Answer 2

希望这会有所帮助：

    var d1 = new DateTime(1990, 1, 1);
    var d2 = new DateTime(1990, 1, 2);
    var d3 = new DateTime(1990, 1, 11);
    var d4 = new DateTime(1990, 1, 12);

    var records = new[] { 
        new { date = d1, freq = 1 }, 
        new { date = d2, freq = 2 }, 
        new { date = d3, freq = 3 }, 
        new { date = d4, freq = 4 } 
    };

    //ticks * WeekDays * DayHours * HourMins * MinSecs
    var weekTicks = (Int64)10000000 * 7 * 24 * 60 * 60;   
    var res = records.GroupBy(x => x.date.Ticks / weekTicks)
             .Select(x => new { week=x.Key ,sum=x.Sum(y=>y.freq)});

这就是结果：

[0] = {week = 99085，sum = 3}

[1] = {week = 99086，sum = 7}

LINQ-to-SQL - 在Date对象中按周分组

2 个答案: