Question

该实体框架是否实际两次访问数据库?

    var result = from p in entities.people where p.id == 6 select p;
    entities.DeleteObject(result);

它袭击我,可能要删除目标,就会迫使第一次旅行取得结果,而反对与之合作的国家将履行删除职能。

如果是这样,我如何避免第二次旅行? 在单一数据库旅行的实体框架中,如何逐个顺序去除?

感谢!

http://www.ohchr.org。

我的原始例子令人误解,因为它是主要钥匙的问答。我怀疑真正的问题是,是否有一种能够从可贵的物品中删除的单程功能。例如:

    var result = from p in entities.people where p.cityid == 6 select p;

    foreach (var r in result)
    {
        entities.DeleteObject(r);
    }

(注意到询问是外国钥匙,因此可能会有多重结果)。

Answer 1

你可以这样做:

  entities.ExecuteStoreCommand("DELETE FROM people WHERE people.cityid={0}", 6);

这是对数据库的一次访问,可以肯定并有效。

EDIT: Also, take a look here, they suggest the same solution. And to answer the question, this is the only way to delete entities, not referenced by primary key, from a database using entity framework, without fetching these entities (and without writing some helper extension methods like suggested in this answer).

Answer 2

直接删除:

var people = new people() { id = 6 };
entities.people.Attach(people);
entities.people.Remove(people);
entities.SaveChanges();

如果你想看到它的话,fire up aprofiler 。

EDIT:

这将使你能够使用Linq,但只得一次。

var peopleToDelete = entities.people.Where(p => p.id == 6);

foreach (var people in peopleToDelete )
    entities.people.DeleteObject(people );

entities.SaveChanges();

从欧洲自由贸易区的盒子中看,没有容易做到这一点,事实上(只要不想使用直接的<代码>SQL,我个人不使用该密码)。另一张海报之一链接到以下答案:,其中利用

友情链接