如何使用实体框架按日期分组而不是按时间分组 [英] how to use entity framework to group by date not date with time

问题描述

我的代码:

//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() };

此代码将引发异常，例如实体框架不支持get Date操作. 因为log.createtime都有日期和时间，所以我想按日期分组，我应该怎么做

this code will throw an exception like entity framework does not support get Date operation. because log.createtime both have date and time, i want to group by date, how should i do

推荐答案

使用

Use EntityFunctions.TruncateTime Method (Nullable<DateTime>). It will be transalated into TRUNCATETIME() TSQL function in generated SQL query, which does what you need:

返回表达式，时间值被截断.

Returns the expression, with the time values truncated.

因此，您的代码应如下所示:

So your code should be as follows:

//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() };

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