如何使用实体框架按日期分组而不是按日期分组

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() };

这段代码会抛出像实体框架一样的异常,不支持get Date操作.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方法(Nullable<DateTime>).它将TRUNCATETIME()在生成的SQL查询中转换为TSQL函数,它可以满足您的需求:

返回表达式,截断时间值.

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

对于更高版本的实体框架，这是一种更简单的方法。

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；