linq-to-entities

问题 public IEnumerable<Table1> GetMatchingTable1(string param, double[] Thicknesses) { return DBContext.Table1.Where(c => c.Field1 == param && Thicknesses.Any(Thickness => Thickness >= c.MinThickness && Thickness <= c.MaxThickness)) .ToList(); } Above query return the following exception. "Some part of your SQL statement is nested too deeply. Rewrite the query or break it up into smaller queries." So far, all my research on the web for this error pointed toward replacing "ANY" with "CONTAINS".

问题 I have a class Counter that counts things by key. Simplified: public class Counter<T> { private Dictionary<T, int> counts; public void Increment(T key) { int current; bool exists = counts.TryGetValue(key, out current); if (exists) { counts[key]++; } else { counts[key] = 1; } } } It does a number of other things specialized to my needs, but that's the essence. So far, it works great. Now I want to enable it to be used in a Linq query (with both the keys and the values). Do to that, I think I

问题 I need to sort by date but the date is stored as text in the database. I am using Linq to entities to perform queries. The way the database is designed it is not feasible to change the column to a date column because many different data types are in that column. There is a descriminator column named type so I will know what type a particular row is. 回答1: You can add a computed column to the table that will convert those strings to dates when your discriminator has a specific value (here I've

问题 In How To Count Associated Entities using Where In Entity Framework I get this query But when I access queryResult[0].post.Category or queryResult[0].post.Tags it´s always empty, because I am not using Include. Include dont work with Projection, as microsoft say at last item here: http://msdn.microsoft.com/en-us/library/bb896317.aspx var queryResult = (from post in posts join comment in comments.Where(x=> x.IsPublic) on post.Id equals comment.Post.Id into g select new { post, post.Author,

问题 I'm working on a model that has two classes, Product and Transaction . public class Product { [DataMember] public Guid ProductId {get; set;} [DataMember] public virtual ICollection<Transaction> Transactions { get; set; } } public class Transaction { [DataMember] public Guid TransactionId {get; set;} [DataMember] public DateTimeOffset Date { get; set; } [DataMember] public String Customer { get; set; } } How do I do a query that will retrieve a product and the Date of its transactions? I tried

问题 I have an expression that I use a few times in several LINQ queries so I separated it out into it's own method that returns the expression. The lambda portion of the function is kind of messy looking. Anyone want to take a crack at refactoring it and making it more readable and/or smaller? private Expression<Func<Message, bool>> UserSelector(string username, bool sent) { return x => ((sent ? x.FromUser : x.ToUser).Username.ToLower() == username.ToLower()) && (sent ? !x.SenderDeleted : !x

问题 I want to write a LINQ to Entity query which does order by ascending or descending based on input parameter, Is there any way for that. Following is the my code. Please suggest. public List<Hosters_HostingProviderDetail> GetPendingApproval(SortOrder sortOrder) { List<Hosters_HostingProviderDetail> returnList = new List<Hosters_HostingProviderDetail>(); int pendingStateId = Convert.ToInt32(State.Pending); //If the sort order is ascending if (sortOrder == SortOrder.ASC) { var hosters = from e

问题 I have an entity called Billings with a property of DateTime. I need to uniquely find the dates so I can go through them and do some stuff. I tried: var DistinctYearMonthsDays = (from t in db.Billings where t.DateTime.HasValue select t.DateTime.Value.Date).Distinct(); foreach (var day in DistinctYearMonthsDays) but I get (on the foreach ): The specified type member 'Date' is not supported in LINQ to Entities. Only initializers, entity members, and entity navigation properties are supported.

问题 Is it possible to use Entity Framework without LINQ (linq to entities)? 回答1: It's not clear what you mean by using Linq to Entities and EF separately. That's a single library EntityFramework.dll . If you want to write queries on plain SQL, you can do it with SqlQuery() method of DbSet class: var users = context.Users.SqlQuery("SELECT * FROM dbo.Users").ToList(); In this case EF acts only as mapper, but it does not generates query. UPDATE According to your comments, you want to avoid

问题 I am using ASP.NET v4.5 and linq to entities I am trying to group my data by week using the below code var groupedByWeek = salesOrdersList .GroupBy(i => i.DueDate.AddDays(-(int)i.DueDate.DayOfWeek)); However I am getting a "yellow screen of death" with the error: LINQ to Entities does not recognize the method 'System.DateTime AddDays(Double)' method, and this method cannot be translated into a store expression. Ideally I would like to put var groupedByWeek = salesOrdersList.GroupBy(i => i