我用linq写的查询为何这么慢

Question

var rows = from rPOTitle in dataSetOrder_Produce.POTitle
           from rAgent in dataSetOrder_Produce.Agent
           from rCustomer in dataSetOrder_Produce.Customer
           from rPODetail in dataSetOrder_Produce.PODetail
           from rPOColor in dataSetOrder_Produce.POColor
           where (rPOTitle.AutoNo == rPODetail.TitleAutoNo) &&
                 (rPODetail.AutoNo == rPOColor.DetailAutoNo) &&
                 (rPODetail.ShipmentDate == Convert.ToDateTime("2007-6-10 0:00:00")) &&
                 (rPOTitle.AgentAutoNo == rAgent.AutoNo) &&
                 (rPOTitle.CustomerAutoNo == rCustomer.AutoNo)
                 select new
                       {
                           PONo = rPOTitle.PONo,
                           HisCount = rPOColor.HisCount,
                           ShipmentDate = rPODetail.ShipmentDate,
                           AgentName = rAgent.AgentName,
                           CustomerCode = rCustomer.CustomerCode
                       };
            
            foreach (var row in rows)
            {
                dataSetOrder_Produce.OrderMaster.Rows.Add(row.PONo,
                                                          row.HisCount,
                                                          row.ShipmentDate,
                                                          row.AgentName,
                                                          row.CustomerCode
                                                          );
                
            }有五张表,第张表都有万几笔数据...我这样写的查询不知道是否得当...慢得厉害...
请高人指点...

Answer 1

多表连接用join语句，不要用where=

Answer 2

像有AutoNo或AutoNo后缀的都是key来的
像rPOTitle.AutoNo 就是对应的 rPODetail.TitleAutoNo
谢谢...

Answer 3

var rows = from rPOTitle in dataSetOrder_Produce.POTitle
           join rAgent in dataSetOrder_Produce.Agent
           on rPOTitle.AgentAutoNo equals rAgent.AutoNo
           join rCustomer in dataSetOrder_Produce.Customer
           on rPOTitle.CustomerAutoNo equals rCustomer.AutoNo
           join rPODetail in dataSetOrder_Produce.PODetail 
           on rPOTitle.AutoNo equals rPODetail.TitleAutoNo
           join rPOColor in dataSetOrder_Produce.POColor
           on rPODetail.AutoNo equals rPOColor.DetailAutoNo            where (rPODetail.ShipmentDate == Convert.ToDateTime("2007-6-10 0:00:00"))           select new
           {
              PONo = rPOTitle.PONo,
              HisCount = rPOColor.HisCount,
              ShipmentDate = rPODetail.ShipmentDate,
              AgentName = rAgent.AgentName,
              CustomerCode = rCustomer.CustomerCode
              };
           foreach (var row in rows)
           {
                    dataSetOrder_Produce.OrderMaster.Rows.Add(row.PONo,
                                                              row.HisCount,
                                                              row.ShipmentDate,
                                                              row.AgentName,
                                                              row.CustomerCode
                                                              );
                }不知道这样写对否...
请指点...
谢谢...