entity-framework-4

问题 What's the best way to remove all elements in a System.Data.Entity.DbSet, with Entity Framework 4.3? 回答1: dbContext.Database.ExecuteSqlCommand("delete from MyTable"); (No kidding.) The problem is that EF doesn't support any batch commands and the only way to delete all entities in a set using no direct DML would be: foreach (var entity in dbContext.MyEntities) dbContext.MyEntities.Remove(entity); dbContext.SaveChanges(); Or maybe a litte bit cheaper to avoid loading full entities: foreach

问题 I don't know if there is a better way to use the DbContext because it is not recommended to set is as static when working with WCF . So we are creating it each time we want to access the database. Knowing all the advantages of using Entity Framework, some become useless since we are recreating the DbContext each time; and more may cause overhead since the process of creating big entity models is to be considered. What is your opinion? 回答1: Managing Lifetime You're correct that a single static

问题 I don't know if there is a better way to use the DbContext because it is not recommended to set is as static when working with WCF . So we are creating it each time we want to access the database. Knowing all the advantages of using Entity Framework, some become useless since we are recreating the DbContext each time; and more may cause overhead since the process of creating big entity models is to be considered. What is your opinion? 回答1: Managing Lifetime You're correct that a single static

问题 I'm using entity framework 4 , on inserting a new record using entity framework in a table that have instead of insert trigger while the table has an identity column , the instead of trigger is used to modify one of the inserted value according to certain logic ,Entity framework raises exception "Store update, insert, or delete statement affected an unexpected number of rows (0). Entities may have been modified or deleted since entities were loaded. Refresh ObjectStateManager entries". Can

问题 I am about to start implementing the data access infrastructure of a project that was architected with an approach to DDD ( it's my first attempt on DDD, so be gentle ;-) ). I will be using Entity Framework. Until now, I was looking into the method teached by Julie Lerman on her great book, Programming Entity Framework, where ADO.NET POCO Entity Generator is used, with some changes to the T4 templates and some more custom code. Today I started reading articles on EF4.1 and the ADO.NET

问题 I am about to start implementing the data access infrastructure of a project that was architected with an approach to DDD ( it's my first attempt on DDD, so be gentle ;-) ). I will be using Entity Framework. Until now, I was looking into the method teached by Julie Lerman on her great book, Programming Entity Framework, where ADO.NET POCO Entity Generator is used, with some changes to the T4 templates and some more custom code. Today I started reading articles on EF4.1 and the ADO.NET

问题 Currently when I need to run a query that will be used w/ paging I do it something like this: //Setup query (Typically much more complex) var q = ctx.People.Where(p=>p.Name.StartsWith("A")); //Get total result count prior to sorting int total = q.Count(); //Apply sort to query q = q.OrderBy(p => p.Name); q.Select(p => new PersonResult { Name = p.Name }.Skip(skipRows).Take(pageSize).ToArray(); This works, but I wondered if it is possible to improve this to be more efficient while still using

问题 I am learning some concepts in asp.net mvc. I am using entity framework and visual studio 2013 community edition. I am creating a demo app for learning. I have created model according to this link. The models are as follows. Below is course model. The course has department as foreign key. A department can have many courses. using System; using System.Collections.Generic; using System.Linq; using System.Web; namespace ManyItemsDemo2.Models { public class Course { public int CourseID { get; set

问题 I have been experimenting with Entity Framework 4.4, NHibernate 3.3.1.4000 and SQL Server and I have noticed a difference when it comes to fixing up the relationships when you commit your changes, and I was wondering what is the best practice or if I'm doing something wrong. Here's what I tested. I have a classic Parent linked to n Children. I have 2 parents in the database with 20 children each. I load both parents, and I take the first child of the first parent and assign that child the

问题 I have been experimenting with Entity Framework 4.4, NHibernate 3.3.1.4000 and SQL Server and I have noticed a difference when it comes to fixing up the relationships when you commit your changes, and I was wondering what is the best practice or if I'm doing something wrong. Here's what I tested. I have a classic Parent linked to n Children. I have 2 parents in the database with 20 children each. I load both parents, and I take the first child of the first parent and assign that child the