C# 从实体框架中删除单个记录？

Delete a single record from Entity Framework?

提问by user2497476

I have a SQL Server table in Entity Framework named employwith a single key column named ID.

我在实体框架中有一个 SQL Server 表，它employ以一个名为ID.

How do I delete a single record from the table using Entity Framework?

如何使用实体框架从表中删除单个记录？

采纳答案by mt_serg

It's not necessary to query the object first, you can attach it to the context by its id. Like this:

不必先查询对象，您可以通过其 id 将其附加到上下文。像这样：

var employer = new Employ { Id = 1 };
ctx.Employ.Attach(employer);
ctx.Employ.Remove(employer);
ctx.SaveChanges();

Alternatively, you can set the attached entry's state to deleted :

或者，您可以将附加条目的状态设置为已删除：

var employer = new Employ { Id = 1 };
ctx.Entry(employer).State = EntityState.Deleted;
ctx.SaveChanges();

回答by Mansfield

You can use SingleOrDefaultto get a single object matching your criteria, and then pass that to the Removemethod of your EF table.

您可以使用SingleOrDefault获取与您的条件匹配的单个对象，然后将其传递给Remove您的 EF 表的方法。

var itemToRemove = Context.Employ.SingleOrDefault(x => x.id == 1); //returns a single item.

if (itemToRemove != null) {
    Context.Employ.Remove(itemToRemove);
    Context.SaveChanges();
}

回答by Sam Leach

Employer employer = context.Employers.First(x => x.EmployerId == 1);

context.Customers.DeleteObject(employer);
context.SaveChanges();

回答by Alex G

  var stud = (from s1 in entities.Students
            where s1.ID== student.ID
            select s1).SingleOrDefault();

  //Delete it from memory
  entities.DeleteObject(stud);
  //Save to database
  entities.SaveChanges();

回答by Baqer Naqvi

I am using entity framework with LINQ. Following code was helpful for me;

我在 LINQ 中使用实体框架。以下代码对我有帮助；

1- For multiple records

1- 对于多条记录

 using (var dbContext = new Chat_ServerEntities())
 {
     var allRec= dbContext.myEntities;
     dbContext.myEntities.RemoveRange(allRec);
     dbContext.SaveChanges();
 }

2- For Single record

2- 对于单条记录

 using (var dbContext = new Chat_ServerEntities())
 {
     var singleRec = dbContext.ChatUserConnections.FirstOrDefault( x => x.ID ==1);// object your want to delete
     dbContext.ChatUserConnections.Remove(singleRec);
     dbContext.SaveChanges();
 }

回答by valentasm

More generic approuch

更通用的方法

public virtual void Delete<T>(int id) where T : BaseEntity, new()
{
    T instance = Activator.CreateInstance<T>();
    instance.Id = id;
    if (dbContext.Entry<T>(entity).State == EntityState.Detached)
    {
        dbContext.Set<T>().Attach(entity);
    }

    dbContext.Set<T>().Remove(entity);
}

回答by Namroy

    [HttpPost]
    public JsonResult DeleteCotnact(int id)
    {
        using (MycasedbEntities dbde = new MycasedbEntities())
        {
            Contact rowcontact = (from c in dbde.Contact
                                     where c.Id == id
                                     select c).FirstOrDefault();

            dbde.Contact.Remove(rowcontact);
            dbde.SaveChanges();

            return Json(id);
        }
    }

What do you think of this, simple or not, you could also try this:

你怎么看这个，简单与否，你也可以试试这个：

        var productrow = cnn.Product.Find(id);
        cnn.Product.Remove(productrow);
        cnn.SaveChanges();

回答by Tom Trnka

For generic DAO my work finnaly this:

对于通用 DAO，我的工作最终是这样的：

    public void Detele(T entity)
    {
        db.Entry(entity).State = EntityState.Deleted;
        db.SaveChanges();
    }

回答by Mohammad Reza Sadreddini

Using EntityFramework.Pluscould be an option:

使用EntityFramework.Plus可能是一种选择：

dbContext.Employ.Where(e => e.Id == 1).Delete();

More examples are available here

此处提供更多示例

回答by Sikander Iqbal

u can do it simply like this

你可以像这样简单地做到这一点

   public ActionResult Delete(int? id)
    {
        using (var db = new RegistrationEntities())
        {
            Models.RegisterTable Obj = new Models.RegisterTable();
            Registration.DAL.RegisterDbTable personalDetail = db.RegisterDbTable.Find(id);
            if (personalDetail == null)
            {
                return HttpNotFound();
            }
            else
            {
                Obj.UserID = personalDetail.UserID;
                Obj.FirstName = personalDetail.FName;
                Obj.LastName = personalDetail.LName;
                Obj.City = personalDetail.City;

            }
            return View(Obj);
        }
    }


    [HttpPost, ActionName("Delete")]

    public ActionResult DeleteConfirmed(int? id)
    {
        using (var db = new RegistrationEntities())
        {
            Registration.DAL.RegisterDbTable personalDetail = db.RegisterDbTable.Find(id);
            db.RegisterDbTable.Remove(personalDetail);
            db.SaveChanges();
            return RedirectToAction("where u want it to redirect");
        }
    }

model

模型

 public class RegisterTable
{

    public int UserID
    { get; set; }


    public string FirstName
    { get; set; }


    public string LastName
    { get; set; }


    public string Password
    { get; set; }


    public string City
    { get; set; }

} 

view from which u will call it

你会从中调用它的视图

 <table class="table">
    <tr>
        <th>
            FirstName
        </th>
        <th>
            LastName
        </th>

        <th>
            City
        </th>
        <th></th>
    </tr>

    @foreach (var item in Model)
    {
        <tr>
            <td> @item.FirstName </td>
            <td> @item.LastName </td>
            <td> @item.City</td>
            <td>
                <a href="@Url.Action("Edit", "Registeration", new { id = item.UserID })">Edit</a> |
                <a href="@Url.Action("Details", "Registeration", new { id = item.UserID })">Details</a> |
                <a href="@Url.Action("Delete", "Registeration", new { id = item.UserID })">Delete</a>

            </td>
        </tr>

    }

</table>

i hope this will be easy for u to understand

我希望这对你来说很容易理解