ef6中的启用触发器后出现错误“ System.Data.Entity.Infrastructure.DbUpdateException”

Question

通过执行该命令，我删除了该表的行，没有任何问题。

using (var context = new SamenEntities())
{
    var person = context.regs.Where(c => c.code == ID).FirstOrDefault();
    if (person != null)
    {
        context.regs.Remove(person);
        context.SaveChanges();
        clearformsearch();
    }
}

现在，我想在数据库中激活以下触发器：

    USE [Samen]
GO
/****** Object:  Trigger [dbo].[delete_after_project]    Script Date: 9/11/2018 12:46:09 AM ******/
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
ALTER TRIGGER [dbo].[delete_after_project]
ON [dbo].[reg]
AFTER Delete
AS 
BEGIN   
SET NOCOUNT ON;
DECLARE @C_ID AS int
SELECT @C_ID = code FROM deleted 
DELETE FROM project
WHERE id_person = @C_ID
END

激活触发器后，我在SaveChange中收到以下错误：

  

System.Data.Entity.Infrastructure.DbUpdateException ：'更新条目时发生错误。请参阅内部异常   详细信息。”