CODEWITHSUNDEEP
c#-4.0lambdalinq-to-entities
DeveloperDavid
DeveloperDavid

Reputation: 157

Linq to entities get first or last from 2million rows

I'm learning LINQ to Entities in C# .NET4.0 Winforms.

I have a MSSQL database table with over 2million rows, eventually more and I need to just pull back the first record or the last record in the database.

I tried getting the last record but it doesn't seem to want to work for me :( It builds okay, but during RunTime I get a 

LINQ to Entities does not recognize the method 'StockTraderRobotDT.IntradayFuturesTick       
Last[IntradayFuturesTick](System.Linq.IQueryable`1[StockTraderRobotDT.IntradayFuturesTick])' 
method, and this method cannot be translated into a store expression.

I'm doing this... 

using (DataFeedEntities db = new DataFeedEntities())
{
   IntradayFuturesTick tick = db.IntradayFuturesTicks.Last();
}

I know it's probably an easy answer but I'm still getting my head around LINQ.

Thanks for your help.

David

Upvotes: 0

Views: 2565

Answers (2)

Hamit YILDIRIM
Hamit YILDIRIM

Reputation: 4549

db.IntradayFuturesTicks.OrderByDescending(x => x.Id).FirstOrDefault();

Upvotes: 0

Charles Graham
Charles Graham

Reputation: 1157

You need to sort the results in descending order then use the Take extension method.

using (DataFeedEntities db = new DataFeedEntities())
{
    IntradayFuturesTick tick = db.IntradayFuturesTicks
       .OrderByDescending(x => x.Id)
       .Take(1)
       .Single();
}

You could also use First instead of Take, but I'm not sure if that will return only a single result in the database query.

Upvotes: 4

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