当我不小心试图更新对象而不是保存时，我得到了这个问题!

我有

 if (IsNewSchema(model))
            unitOfWork.SchemaRepository.Update(schema);
        else
            unitOfWork.SchemaRepository.Insert(schema);

我本应该这样做的

 if (IsNewSchema(model))
            unitOfWork.SchemaRepository.Insert(schema);
        else
            unitOfWork.SchemaRepository.Update(schema);

我也遇到了同样的问题。

我使用EF 6，代码优先+迁移。 问题是我们的DBA在抛出错误的表上创建了一个约束。

我在使用Telerik的RadGrid时遇到了这个问题。我将主键设置为只读的绑定列。如果列是display="false"，它会工作得很好，但readonly="true"导致了问题。我通过将绑定列display=false并添加一个单独的模板列来解决这个问题

<telerik:GridBoundColumn HeaderText="Shouldnt see" Display="false" 
     UniqueName="Id" DataField="Id">
</telerik:GridBoundColumn>
<telerik:GridTemplateColumn HeaderText="Id" UniqueName="IdDisplay">
    <ItemTemplate>
        <asp:Label ID="IDLabel" runat="server" 
            Text='<%# Eval("Id") %>'></asp:Label>                               
    </ItemTemplate>
</telerik:GridTemplateColumn> 

我遇到这种情况是因为datetime和datetime2之间不匹配。奇怪的是，在测试人员发现问题之前，它工作得很好。我的Code First模型包括一个DateTime作为主键的一部分:

[Key, Column(Order = 2)]  
public DateTime PurchasedDate { get; set; } = (DateTime)SqlDateTime.MinValue;

生成的列是一个datetime列。当调用SaveChanges时，EF生成了以下SQL:

-- Region Parameters
DECLARE @0 Int = 2
DECLARE @1 Int = 25
DECLARE @2 Int = 141051
DECLARE @3 DateTime2 = '2017-07-27 15:16:09.2630000' --(will not equal a datetime value)
-- EndRegion
UPDATE [dbo].[OrganizationSurvey]
SET [OrganizationSurveyStatusId] = @0
WHERE ((([SurveyID] = @1) AND ([OrganizationID] = @2)) AND ([PurchasedDate] = @3))

因为它试图将datetime列与datetime2值匹配，所以没有返回任何结果。我能想到的唯一解决方案是将列更改为datetime2:

[Key, Column(Order = 2, TypeName = "DateTime2")]  
public DateTime PurchasedDate { get; set; } = (DateTime)SqlDateTime.MinValue;

我得到了这个异常，我设置id列为自动增量在我的数据库的表，然后它工作得很好

Got the same problem when removing item from table(ParentTable) that was referenced by another 2 tables foreign keys with ON DELETE CASCADE rule(RefTable1, RefTable2). The problem appears because of "AFTER DELETE" trigger at one of referencing tables(RefTable1). This trigger was removing related record from ParentTable as result RefTable2 record was removed too. It appears that Entity Framework, while in-code was explicitly set to remove ParentTable record, was removing related record from RefTable1 and then record from RefTable2 after latter operation this exception was thrown because trigger already removed record from ParentTable which as results removed RefTable2 record.