Question

mycode的：

//get data
        var myData = from log in db.OperationLogs
                     group log by log.CreateTime.Date  into g
                     orderby g.Key
                     select new { CreateTime = g.Key, Count = g.Count() };

这个代码会抛出一个异常，就像实体框架不支持get Date操作一样。因为log.createtime都有日期和时间，我想按日期分组，我该怎么做

Answer 1

使用EntityFunctions.TruncateTime Method (Nullable<DateTime>)。它将被转换为生成的SQL查询中的TRUNCATETIME() TSQL函数，它可以满足您的需求：

返回表达式，时间值被截断。

所以你的代码应该如下：

//get data
var myData = from log in db.OperationLogs
             group log by EntityFunctions.TruncateTime(log.CreateTime) into g
             orderby g.Key
             select new { CreateTime = g.Key, Count = g.Count() };

Answer 2

     var result = from s in entitiesModel.TvysFuelTankDatas
                           orderby s.Datetime ascending
                           group s by new { y = s.Datetime.Year, m = s.Datetime.Month + "/", d = s.Datetime.Day + "/" } into g
                           select new WellDrillData { Date = Convert.ToDateTime(g.Key.d.ToString() + g.Key.m.ToString() + g.Key.y.ToString()), Depth = (double)g.Sum(x => x.Difference) };

              List<WellDrillData> dailyFuelConsumptions = result.ToList();

Answer 3

这里有一种更简单的方法可以为以后的实体框架版本做到这一点。

var query = Data
.GroupBy(o => new { EventDate = o.EventDate.Date })
.Select(s => new SalesData()
{
    EventDate = s.Key.EventDate,
    Amount = s.Sum(o => o.Amount),
    Qty = s.Sum(o => o.Qty),
    RefundAmount = s.Sum(o => o.RefundAmount),
    RefundQty = s.Sum(o => o.RefundQty),
})
.OrderBy(o => o.EventDate)
.ToList();

返回查询；

如何使用实体框架按日期分组而不是按日期分组

3 个答案: