尝试循环Linq查询结果时出错

我需要提取与特定值（

CourseCode

）对应的任意数量的记录，并将这些记录插入到另一个表中。只要

Linq

代码只返回一条记录，此代码就可以正常工作，但是如果有超过一条记录，我会收到以下消息：

ObjectStateManager中已存在具有相同密钥的对象。 现有对象处于“修改”状态。对象只能是 如果ObjectStateManager位于已添加的

下面是我的代码：

            if (_db == null) _db = new AgentResourcesEntities();

            var prodCodes = from records in _db.CourseToProduct
                              where records.CourseCode == course.CourseCode
                              select records;

            foreach (var pt in prodCodes.ToList())
            {
                agentProdTraining.SymNumber = symNumber;
                agentProdTraining.CourseCode = course.CourseCode;
                agentProdTraining.ProductCode = pt.ProductCode;
                agentProdTraining.DateTaken = course.DateTaken;
                agentProdTraining.Method = course.Method;
                agentProdTraining.LastChangeOperator = requestor;
                agentProdTraining.LastChangeDate = DateTime.Now;
                agentProdTraining.DateExpired = course.ExpirationDate;
                agentProdTraining.ProductCode = pt.ProductCode;
                agentProdTraining.NoteId = pt.NoteId;

                _db.AgentProductTraining.AddObject(agentProdTraining);
                _db.SaveChanges();

                PtAdded++;

                EventLog.WriteEntry(sSource, "Product Training added", EventLogEntryType.Warning);
            }

---

即使属性值已更改，循环仍在重新添加相同的agentProdTraining对象。为每个循环执行创建一个新实例

foreach (var pt in prodCodes.ToList())
{
  var agentProdTraining = new AgentProductTraining();

  agentProdTraining.SymNumber = symNumber;
  agentProdTraining.CourseCode = course.CourseCode;
  agentProdTraining.ProductCode = pt.ProductCode;
  agentProdTraining.DateTaken = course.DateTaken;
  agentProdTraining.Method = course.Method;
  agentProdTraining.LastChangeOperator = requestor;
  agentProdTraining.LastChangeDate = DateTime.Now;
  agentProdTraining.DateExpired = course.ExpirationDate;
  agentProdTraining.ProductCode = pt.ProductCode;
  agentProdTraining.NoteId = pt.NoteId;

  _db.AgentProductTraining.AddObject(agentProdTraining);
  _db.SaveChanges();

  PtAdded++;

  EventLog.WriteEntry(sSource, "Product Training added", EventLogEntryType.Warning);
}

---

即使属性值已更改，循环仍在重新添加相同的agentProdTraining对象。为每个循环执行创建一个新实例

foreach (var pt in prodCodes.ToList())
{
  var agentProdTraining = new AgentProductTraining();

  agentProdTraining.SymNumber = symNumber;
  agentProdTraining.CourseCode = course.CourseCode;
  agentProdTraining.ProductCode = pt.ProductCode;
  agentProdTraining.DateTaken = course.DateTaken;
  agentProdTraining.Method = course.Method;
  agentProdTraining.LastChangeOperator = requestor;
  agentProdTraining.LastChangeDate = DateTime.Now;
  agentProdTraining.DateExpired = course.ExpirationDate;
  agentProdTraining.ProductCode = pt.ProductCode;
  agentProdTraining.NoteId = pt.NoteId;

  _db.AgentProductTraining.AddObject(agentProdTraining);
  _db.SaveChanges();

  PtAdded++;

  EventLog.WriteEntry(sSource, "Product Training added", EventLogEntryType.Warning);
}