实体框架不按预期运行 [英] Entity Framework Not Operating as Expected

问题描述

我正在使用 http：// msdn.microsoft.com/en-us/data/jj591506 。

using (var db = new DatabaseEntities())
{
            // Section 1
            var section = new Section
            {
                SectionID = 1,
                SectionLetter = "d"
            };
            db.Sections.Add(section);
            db.SaveChanges();

            // Section 2

            var query = from b in db.Sections 
                        orderby b.SectionLetter
                        select b;

            foreach (var item in query)
            {
                this.Title = item.SectionLetter;
            }
}

当我使用代码的第1节和第2节在一起他们工作得很好。然而，当我运行第2节时，标题不会改变，这意味着它甚至不返回单个项目，因此不会进入foreach循环。我不明白为什么它不会进入循环。

When I use section 1 and section 2 of the code above together they work well. However, when I run just Section 2 the title does not change which means it does not even return a single item and thus does not enter the foreach loop. I can't see why it would not enter the loop.

我意识到这个问题可能是一个明显的答案，但我认为我应该问stackoverflow而不是问一个同事，所以有同样问题的人可以找到答案。

I realise there is probably an obvious answer to this question but I thought I should ask on stackoverflow rather than ask a colleague so others with the same question could find an answer.

我怀疑这个问题可能有一个线索： System.Data.Entity不能按照MVC实体框架的预期工作。不幸的是，我似乎不能工作。

I suspect there might be a clue in this question: System.Data.Entity not working as expected for MVC Entity Framework. Unfortunately I can't seem to work it out.

推荐答案

它看起来像行 var db = new DatabaseEntities（）正在连接到没有任何行的数据库。检查连接属性 db 以确保它位于正确的服务器/实例/文件上。

It looks like the line var db = new DatabaseEntities() is connecting to a database that doesn't have any rows. Check the Connection property of db to make sure it is on the correct server/instance/file.

如果您在 query.ToArray（）上执行快速观察，您应该可以看到表的内容。

You should be able to see the contents of the table if you perform a "Quick Watch" on query.ToArray().

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