在LINQ查询中无时间返回日期 [英] Returning dates without times in a LINQ query

问题描述

我正在编写一个查询，我想计算我们的呼叫中心按日期联系的次数。看起来很简单，但是由于联系人日期字段是一个datetime字段，所以我得到时间，所以当我按联系日期（时间）分组时，每个联系人日期实例都有一个'1'。所以，我只想按时间分组。以下是我用来查询数据库的表达式：

  MyDataContext db = new MyDataContext（）; 
 var items =（from h in db.ContactHistories 
 group h by h.contact_dt into g 
 orderby g.Key 
 select new 
 {
 contact_dt = g.Key，
 item_count = g.Count（）
}）。（50）; 
  

我试图使用

  h.contact_dt.ToShortDateString（）
  

但这不工作，因为SQL确实知道ToShortDateString（）。非常感谢任何想法。

感谢！

编辑：

.Take（50）是为了限制我得到的记录数，直到我添加日期选择器和where子句，所以我没有得到所有的400K记录。 ;）

解决方案

使用 Date property：

  group h by h.contact_dt.Date into g 
  

LINQ to SQL知道这一点 - 请参阅这个方便的页面的理解方法和属性。

编辑：好的，所以直接分组不起作用...我们试图给它一点的帮助：

  var items =（from h in db.ContactHistories 
 select h.Date into date 
组日期到g 
 orderby g.Key 
选择新
 {
 contact_dt = g.Key，
 item_count = g.Count（）$ b $ （50）; 
  

我不知道是否可以正常工作，但值得一试...

I am writing a query where I want to count the number of times our call center gets contacted by date. Seems easy enough, but since the contact date field is a datetime field I get the time, so when I group by contact date(time) each contact date instance has a count of '1'. So, I want to group by just the date without the time. Below is the expression I use to query the database:

MyDataContext db = new MyDataContext();
var items = (from h in db.ContactHistories
             group h by h.contact_dt into g
             orderby g.Key
             select new
             {
                 contact_dt = g.Key,
                 item_count = g.Count()
             }).Take(50);

I've tried to use

     h.contact_dt.ToShortDateString()

But that doesn't work since SQL does know about ToShortDateString(). Any thoughts are greatly appreciated.

Thanks!

EDIT:

The .Take(50) is in place to limit the number of records I get until I add the date pickers and a where clause so I don't get all 400K records. ;)

解决方案

Use the Date property:

group h by h.contact_dt.Date into g

LINQ to SQL knows about that - see this handy page of "understood" methods and properties.

EDIT: Okay, so grouping directly doesn't work... how about we try to give it a bit of help:

var items = (from h in db.ContactHistories
             select h.Date into date
             group date by date into g
             orderby g.Key
             select new
             {
                 contact_dt = g.Key,
                 item_count = g.Count()
             }).Take(50);

I don't know if it'll work, but it's worth a try...

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