var user = this.dataContext.Users.FirstOrDefault( p => p.User_ID == 250 && p.UserName == “Jack”); The p => at the beginning counts for the whole expression. The syntax used here is a shorthand for (p) => { return p.User_ID == 250 && p.UserName == “Jack”; }
AFAIK, this isn’t supported by the object model. However, LINQ supports a method to execute a query (strangly enough called DataContext.ExecuteQuery). Looks like you can use that to call a arbitrary piece of SQL and map it back to LINQ. You won’t be SQL free because of the embedded SQL, but you won’t have to … Read more
Have you looked at SqlMetal? It’s officially supported, although not promoted too much. You can use it to build dbmls from the commandline – we’ve used it as part of a db’s continous integration updates (make sure you have really good code separation if you do this though – partial classes are a saviour – … Read more
You need to import the namespace into your view by adding @using System.Data.Linq at the top of your view. However if you want it in all your views then you need to add <add namespace=”System.Data.Linq” /> to the web.config in your Views folder: <system.web.webPages.razor> <host factoryType=”System.Web.Mvc.MvcWebRazorHostFactory, System.Web.Mvc, Version=3.0.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35″ /> <pages pageBaseType=”System.Web.Mvc.WebViewPage”> <namespaces> <add … Read more
How can I do an orderby thenby using the above syntax without using extension syntax. Use a comma between the fields: orderby a, b And what does the orderby, orderby do? When you use orderby twice in a row the elements conceptually will first be sorted using the first orderby, and then sorted again using … Read more
This problem occurs whenever the designer cannot figure out the return type of the SP. Same problem and solutions described here How to get multiple result set of procedure using LINQ to SQL Basically this is the solution from the link: Avoid using #temp Table in your stored procedure, instead of you can use Table … Read more
Entities can be created outside of queries and inserted into the data store using a DataContext. You can then retrieve them using queries. However, you can’t create entities as part of a query.
It depends on what behavior you want. Returning an IList<T> tells the caller that they’ve received all of the data they’ve requested Returning an IEnumerable<T> tells the caller that they’ll need to iterate over the result and it might be lazily loaded. Returning an IQueryable<T> tells the caller that the result is backed by a … Read more
If Ids is a List, array or similar, L2S will translate into a contains. If Ids is a IQueryable, just turn it into a list before using it in the query. E.g.: List<int> listOfIDs = IDs.ToList(); var query = from st in dc.SomeTable where listOfIDs.Contains(st.ID) select …..
This is what I found seems like you still have to do a group by…can just use constant: var orderTotals = from ord in dc.Orders group ord by 1 into og select new { prop1 = og.Sum(item=> item.Col1), prop2 = og.Sum(item => item.Col2), prop3 = og.Count(item => item.Col3) }; This produces the following SQL, which … Read more