EF code第一：无法插入表'mytable的“标识列显式值时IDENTITY_INSERT设置为OFF [英] EF Code first : Cannot insert explicit value for identity column in table 'myTable' when IDENTITY_INSERT is set to OFF

问题描述

在设置数据库（SQL Server）的主键标识

在使用EF中插入数据，我得到错误

  

无法插入的标识列显式值'myTable的'
  当IDENTITY_INSERT设置为OFF

这个特定的实体，尽管我使用与其他实体同样的方法来插入数据并没有得到错误和他们在一起。

 公共类的MyTable
    {
    [按键/ *，DatabaseGenerated（DatabaseGeneratedOption.Identity）* /]
    公众诠释ID {获取;设置;}
    公共字符串名称{;设置;}
    公共字符串类型{获取;设置;}
    公共字符串状态{获取;设置;}
    公众诠释国家{获取;设置;}
    公开日期时间起始日期{获取;设置;}
    公众的DateTime DUE_DATE {获取;设置;}
    }`
 

查询

  MyTable的检查=新MyTable的（）;
            check.name =检查名;
            check.type =DB;
            check.status =新;
            check.country =国家;
            check.start_date = DateTime.Now;
            check.due_date =的dueDate;
            db.myTables.Add（检查）;
            db.SaveChanges（）;
 

更新

注释上面行后

 （DatabaseGenerated（DatabaseGeneratedOption.Identity））
 

它抛出一个异常

  

在ReferentialConstraint从属属性映射到一个
  存储生成列。专栏：ID

解决方案

我不知道这是否是你的情况太....但第二个错误says..you使用的是主键在一些外键这关系仅适用于有DatabaseGeneratedOption.None属性。

因此​​，要使用你的主键标识可以用DatabaseGeneratedOption.Identity装饰它

在这种情况下，它会抛出一个异常，因为你不能用身份关系（使用DatabaseGeneratedOption.None代替）。

Set the primary key to identity in database (SQL Server)

When using EF to insert data I am getting error

Cannot insert explicit value for identity column in table 'myTable' when IDENTITY_INSERT is set to OFF

with this particular entity, though I am using the same approach with other entities to insert the data and getting no error with them.

   public class MyTable 
    {
    [Key/*,DatabaseGenerated(DatabaseGeneratedOption.Identity)*/]
    public int ID{get;set;}
    public string name {get;set;}
    public string type {get;set;}
    public string status {get;set;}
    public int country {get;set;}
    public DateTime start_date {get;set;}
    public DateTime due_date {get;set;}
    }`

Query

    MyTable check= new MyTable();
            check.name = checkName;
            check.type = "DB";
            check.status = "New";
            check.country = country;
            check.start_date = DateTime.Now;
            check.due_date = dueDate;
            db.myTables.Add(check);
            db.SaveChanges();

Updated :

After uncommenting the above line

(DatabaseGenerated(DatabaseGeneratedOption.Identity)) 

it's throwing an exception

A dependent property in a ReferentialConstraint is mapped to a store-generated column. Column: 'ID'

解决方案

I am not sure if it is in your case too....but the second error says..you are using your primary key as foreign key in some relation which is only valid for property having DatabaseGeneratedOption.None .

So to use your primary key as identity you can decorate it with DatabaseGeneratedOption.Identity
and in that case it will throw an exception because you can not use identity for relation(use DatabaseGeneratedOption.None instead).

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