存储更新、插入或删除语句在删除实体时影响了意外的行数 (0)

Question

我有一个 _job 对象，这个 _job 对象有相关的工作。当我删除相关工作时，我收到了这个错误：

{"存储更新、插入或删除语句影响了意外 行数 (0)。实体可能已被修改或删除 实体已加载。看 http://go.microsoft.com/fwlink/?LinkId=472540 获取有关信息 理解和处理乐观并发异常。"}

这是我的代码：

      if (_job.relatedJobs.Any())
        {


            foreach(var relatedJob in _job.relatedJobs.ToList())
            {
                jobList.Add(relatedJob );
                _job.relatedJobs.Remove(relatedJob);
            }

            _db.Entry(_job).State = EntityState.Modified;
        }
       _db.Jobs.Add(_job);
       _db.SaveChanges(); //I'm getting the exception at this line

我该如何解决这个问题？谢谢。

Answer 1

这行得通。

以下是创建数据库表的方法，使用您的数据库而不是我的 breaz 数据库名称：

USE [Breaz]
GO
/****** Object:  Table [dbo].[Job]    Script Date: 1/12/2017 10:00:24 AM ******/
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
SET ANSI_PADDING ON
GO
CREATE TABLE [dbo].[Job](
    [Id] [int] IDENTITY(1,1) NOT NULL,
    [JobDescription] [varchar](50) NULL,
 CONSTRAINT [PK_Job] PRIMARY KEY CLUSTERED 
(
    [Id] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]
) ON [PRIMARY]

GO
SET ANSI_PADDING OFF
GO
/****** Object:  Table [dbo].[JobRelated]    Script Date: 1/12/2017 10:00:24 AM ******/
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
SET ANSI_PADDING ON
GO
CREATE TABLE [dbo].[JobRelated](
    [Id] [int] IDENTITY(1,1) NOT NULL,
    [JobId] [int] NULL,
    [RelatedJobDescription] [varchar](10) NULL,
 CONSTRAINT [PK_JobRelated] PRIMARY KEY CLUSTERED 
(
    [Id] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]
) ON [PRIMARY]

GO
SET ANSI_PADDING OFF
GO
SET IDENTITY_INSERT [dbo].[Job] ON 

GO
INSERT [dbo].[Job] ([Id], [JobDescription]) VALUES (1, N'Cleaning')
GO
SET IDENTITY_INSERT [dbo].[Job] OFF
GO
SET IDENTITY_INSERT [dbo].[JobRelated] ON 

GO
INSERT [dbo].[JobRelated] ([Id], [JobId], [RelatedJobDescription]) VALUES (3, 1, N'Mopping')
GO
INSERT [dbo].[JobRelated] ([Id], [JobId], [RelatedJobDescription]) VALUES (4, 1, N'Sweeping')
GO
SET IDENTITY_INSERT [dbo].[JobRelated] OFF
GO
ALTER TABLE [dbo].[JobRelated]  WITH CHECK ADD  CONSTRAINT [FK_JobRelated_Job] FOREIGN KEY([JobId])
REFERENCES [dbo].[Job] ([Id])
GO
ALTER TABLE [dbo].[JobRelated] CHECK CONSTRAINT [FK_JobRelated_Job]
GO

为这两个表创建一个 ADO.NET 实体数据模型 (EDMX)

这是你的控制器：

public ActionResult Index12()  //this Method name can change
    {

        using (BreazEntities2 e = new BreazEntities2())  //you will use the dbcontext name you have
        {
            try
            {

                var _job = e.Jobs.Find(1);
                if (_job.JobRelateds.Any())
                {
                    foreach (var relatedJob in _job.JobRelateds.ToList())
                    {
                        Job addToJob = new Job();

                        //no relateds for this
                        addToJob.JobDescription = "From related to Job->" + relatedJob.RelatedJobDescription;
                        e.Jobs.Add(addToJob);
                        e.JobRelateds.Remove(relatedJob);
                    }
                }
                e.SaveChanges();
            }
            catch (DbEntityValidationException ex)
            {
                foreach (var failure in ex.EntityValidationErrors)
                {
                    string validationErrors = "";

                    foreach (var error in failure.ValidationErrors)
                    {
                        validationErrors += error.PropertyName + "  " + error.ErrorMessage;
                    }
                }
            }
        }
        return View();
    }