C# 使用 lambda 查询获取前 5 个值

Get top 5 values with lambda query

提问by zey

Here is my code,

这是我的代码，

rptAnnouncement.DataSource = DbContext.Announcements
    .Where(n => n.Expire_Date.Value.Date >= DateTime.Now.Date)
    .ToList();  

I take the announcements data from database with lambda and bind this data to ASP.NET repeater(rptAnnouncement).

我使用 lambda 从数据库中获取公告数据并将这些数据绑定到 ASP.NET repeater( rptAnnouncement)。

But this query returns all of the data, I just want to get the top 5 (first 5) records like MS SQL Server's select top 5 * from database.

但是此查询返回所有数据，我只想获取前 5 条（前 5 条）记录，例如 MS SQL Server 的select top 5 * from database.

采纳答案by Daniel Imms

You can use OrderBy()to order the elements and then Take()to take the first 5.

您可以使用OrderBy()对元素进行排序，然后Take()使用前 5 个。

rptAnnouncement.DataSource = DbContext.Announcements
    .Where(n => n.Expire_Date.Value.Date >= DateTime.Now.Date)
    .OrderBy(n => n.Expire_Date.Value.Date)
    .Take(5);

Notes

笔记

• You can order descending by using OrderByDescending()
• Calling ToList()and then calling Take()will get all of the items and then take the top 5 as opposed to only getting the top 5.

• 您可以使用降序排序 OrderByDescending()
• 调用ToList()然后调用Take()将获取所有项目，然后获取前 5 项，而不是仅获取前 5 项。

回答by ashutosh raina

If you only want the Top 5 then you can use the below .

如果您只想要前 5 名，则可以使用以下 .

rptAnnouncement.DataSource = DbContext.Announcements.Where(n => n.Expire_Date.Value.Date >= DateTime.Now.Date).Take(5).ToList();

More details here

更多细节在这里

http://msdn.microsoft.com/en-us/library/bb503062.aspx

http://msdn.microsoft.com/en-us/library/bb503062.aspx

回答by Praveen Nambiar

Just use Take(n)in LINQ

只需Take(n)在LINQ

rptAnnouncement.DataSource = DbContext.Announcements
                                      .Where(n => n.Expire_Date.Value.Date >= DateTime.Now.Date)
                                      .Take(5).ToList();