How do I do this
Select top 10 Foo from MyTable
in Linq to SQL?
Use the Take method:
var foo = (from t in MyTable
select t.Foo).Take(10);
In VB LINQ has a take expression:
Dim foo = From t in MyTable _
Take 10 _
Select t.Foo
From the documentation:
Take<TSource>
enumeratessource
and yields elements untilcount
elements have been yielded orsource
contains no more elements. Ifcount
exceeds the number of elements insource
, all elements ofsource
are returned.
@Janei: my first comment here is about your sample ;)
I think if you do like this, you want to take 4, then applying the sort on these 4.
var dados = from d in dc.tbl_News.Take(4)
orderby d.idNews descending
select new
{
d.idNews,
d.titleNews,
d.textNews,
d.dateNews,
d.imgNewsThumb
};
Different than sorting whole tbl_News by idNews descending and then taking 4
var dados = (from d in dc.tbl_News orderby d.idNews descending select new { d.idNews, d.titleNews, d.textNews, d.dateNews, d.imgNewsThumb }).Take(4);
no ? results may be different.
Whether the take happens on the client or in the db depends on where you apply the take operator. If you apply it before you enumerate the query (i.e. before you use it in a foreach or convert it to a collection) the take will result in the "top n" SQL operator being sent to the db. You can see this if you run SQL profiler. If you apply the take after enumerating the query it will happen on the client, as LINQ will have had to retrieve the data from the database for you to enumerate through it
I do like this:
var dados = from d in dc.tbl_News.Take(4)
orderby d.idNews descending
select new
{
d.idNews,
d.titleNews,
d.textNews,
d.dateNews,
d.imgNewsThumb
};
This way it worked for me:
var noticias = from n in db.Noticias.Take(6)
where n.Atv == 1
orderby n.DatHorLan descending
select n;
In VB:
from m in MyTable
take 10
select m.Foo
This assumes that MyTable implements IQueryable. You may have to access that through a DataContext or some other provider.
It also assumes that Foo is a column in MyTable that gets mapped to a property name.
See http://blogs.msdn.com/vbteam/archive/2008/01/08/converting-sql-to-linq-part-7-union-top-subqueries-bill-horst.aspx for more detail.