C# 实体框架，按日期时间按天/周/月分组

正如标题所说，我的表中有一个datetime列

在三种不同的情况下，我需要以三种方式对我的记录进行分组：

按天分组

每周分组

按月分组

如果可能，我如何在实体框架中使用lambda表达式执行这3种不同的group by语句

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更新：链接的问题重复，不是真正的重复。我要的是lambda解决方案，但链接中没有它

您可以使用此方法：

var ByDayGrouped = new TestEntities().Objects.GroupBy(O => new { O.date.Year, O.date.Month, O.date.Day }).ToList();

var ByMonthGrouped = new TestEntities().Objects.GroupBy(O => new { O.date.Year, O.date.Month }).ToList();

var ByWeekGrouped = new TestEntities().Objects.GroupBy(O => (O.date.DayOfYear % 7) + M ).ToList();

用这个

List<MyEntitiy> list = (from e in Context.MyEntities group e by e.Date.Day into g select g).ToList();

和使用

List<MyEntitiy> list = (from e in Context.MyEntities group e by e.Date.GetWeekOfYear() into g select g).ToList();

List List=（从Context.myenties组e中的e到e.Date.GetWeekOfYear（）到g选择g.ToList（）；

可以使用linq和lambda表达式使用以下格式

按天分组

    var results = from p in db.table
                          group p.data by p.DateTime.UtcNow.Day into g
                          select new { Id = g.Key, parameters = g };

按周分组

    var result = from p in db.table
                         group p.data by p.DateTime.UtcNow.DayOfWeek into g
                          select new { Id = g.Key, parameters = g}

否则

    //get the 7days of the week by the below method and perform between operation
    DateTime fromDate = DateTime.Today.Subtract(new TimeSpan(7, 0, 0, 0));
    DateTime today = DateTime.Today;
    var result = from p in db.table
                         group p.data by (DbFunctions.TruncateTime(today) && DbFunctions.TruncateTime(today) >= DbFunctions.TruncateTime(fromDate)) into g
                         select new { Id = g.Key, parameters = g}

这个月也是如此

    DateTime fromDate = DateTime.Today.Subtract(new TimeSpan(30, 0, 0, 0));
    DateTime today = DateTime.Today;
    var result = from p in db.table
                         group p.data by (DbFunctions.TruncateTime(today) && DbFunctions.TruncateTime(today) >= DbFunctions.TruncateTime(fromDate)) into g
                         select new { Id = g.Key, parameters = g}

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是否需要“.Objects”的可能副本？它是什么？“对象”是我的数据库集的名称。它可以是基于您的项目的任何内容

ByweekGroup

查询中的

M

变量是什么？这是一个数字，取决于您希望将一周中的哪一天作为一周的第一天？它有什么用？是否在“参数”中插入“表格”的所有字段？

    DateTime fromDate = DateTime.Today.Subtract(new TimeSpan(30, 0, 0, 0));
    DateTime today = DateTime.Today;
    var result = from p in db.table
                         group p.data by (DbFunctions.TruncateTime(today) && DbFunctions.TruncateTime(today) >= DbFunctions.TruncateTime(fromDate)) into g
                         select new { Id = g.Key, parameters = g}