QueryExpression queryNextSeq = new QueryExpression { EntityName = "ep_prodoperationsequence" };
                            queryNextSeq.Criteria.AddCondition("ep_prodroutingno", ConditionOperator.Equal, ePOS.ep_ProdRoutingNo.Id);
                            queryNextSeq.Criteria.AddCondition(
 
"ep_sequenceno1", ConditionOperator.NotEqual, ePOS.ep_SequenceNo1);
                            queryNextSeq.ColumnSet.AddColumns("ep_prodoperationsequenceid", "ep_sequenceno1", "ep_operationsequence");
                            queryNextSeq.AddOrder("ep_sequenceno1", OrderType.Ascending);

                            queryNextSeq.LinkEntities.Add(
 
new LinkEntity("ep_prodoperationsequence", "ep_operationsequence", "ep_opera                            tionsequence", "ep_operationsequenceid", JoinOperator.Inner));
                            queryNextSeq.LinkEntities[0].Columns.AddColumns("ep_operationsequenceid", "ep_dailywork");//被link實體ep_op                             erationsequence的列
 

                            queryNextSeq.LinkEntities[0].LinkCriteria.AddCondition("ep_dailywork", ConditionOperator.Equal, true);//給                                     被link實體添加條件

                            EntityCollection ecPrdSeq = service.RetrieveMultiple(queryNextSeq);

 foreach (ep_prodoperationsequence item in ecPrdSeq.Entities)
{
  //取被join實體中的列,字典中必須是實體名稱+1,還有就是列數據為null時,要先判斷字典中是否包含該鍵值(就是該列),否則會拋出異常.explain by ldb
  if (item.Attributes.ContainsKey("ep_operationsequence1.ep_dailywork") && item["ep_operationsequence1.ep_dailywork"] != null)
   {
      bool daily  = Convert.ToBeanbool(((AliasedValue)item["ep_operationsequence1.ep_dailywork"]).Value);

   } 
} 

Microsoft dynamic sdk中join應該註意的問題.