c# - LINQ-to-SQL - 在日期对象中按周分组

Question

我正在用 LINQ-to-SQL 编写一个查询，这个查询中有一个日期列。我想按“周”对结果进行分组。我将如何在 LINQ-to-SQL 中执行此操作？

谢谢

Answer 1

假设公历，“第一天”周规则，一周的第一天是星期一。

首日周规则:

Indicates that the first week of the year starts on the first day of the year and ends before the following designated first day of the week

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 ()
    };