Advanced Find for Fetch XML in crm 2011

senario:

if we want to select all opportunity products relating to opportunity:
1. need to select the advanced find.
2. choose the opportunity product entity.
3. check the relation between opportunity and opp.product.
if the 1:N relation name is new_opportunityId and display name is :"opportunity".
in condition:
4. select the opportunity .
5. eqal
6. select the opportunity name.

we will get the Fetch XML like:

<fetch version="1.0" output-format="xml-platform" mapping="logical" distinct="false">

- <entity name="new_opportunityitproduct">

  <attribute name="new_opportunityitproductid" />

  <attribute name="new_name" />

  <attribute name="createdon" />

  <order attribute="new_name" descending="false" />

- <filter type="and">

  <condition attribute="new_opportunityid" operator="eq" uiname="test dates" uitype="opportunity" value="{77470EB8-19CB-E111-9E1C-00155D000B45}" />

  </filter>

  </entity>

  </fetch>

if you want dynamically. remove the value and give the id like:

value="+leadids+"

but in the code we need to give it only single quotation.

In c# code we need give like this:

string fetchquery = "<fetch version='1.0' output-format='xml-platform' mapping='logical' distinct='false'>" +

  "<entity name='new_leaditproduct'>" +

    "<attribute name='new_leaditproductid' />" +

    "<attribute name='new_name' />" +

    "<attribute name='new_category' />" +

    "<attribute name='new_subcategory' />" +

    "<attribute name='new_productservice' />" +

    "<attribute name='createdon' />" +

    "<order attribute='new_name' descending='false' />" +

    "<filter type='and'>" +

      "<condition attribute='new_productid' operator='eq' uitype='lead' value='" + var1.Id + "' />" +

    "</filter>" +

  "</entity>" +

"</fetch>";

then read the fetch xml:

RetrieveMultipleRequest req = new RetrieveMultipleRequest();

                    FetchExpression fetch = new FetchExpression(fetchquery);

                    req.Query = fetch;

                    RetrieveMultipleResponse resp = (RetrieveMultipleResponse)service.Execute(req);

                    //oipt.Id = leadids;

                    EntityCollection col = resp.EntityCollection;

reading the values.

Entity opp_product = new Entity();

                    opp_product.LogicalName = "new_opportunityitproduct";

                    EntityReference opp = new EntityReference();

                    opp.Id = entity.Id;

                    opp.LogicalName = entity.LogicalName;

foreach (var c in col.Entities)

                    {

                        opp_product["new_category"] = (EntityReference)c["new_category"];

                        opp_product["new_subcategory"] = (EntityReference)c["new_subcategory"];

                        opp_product["new_productservice"] = (EntityReference)c["new_productservice"];

                        opp_product["new_price"] = new Money() { Value = 0 };

                        opp_product["new_opportunityid"] = (EntityReference)opp;

                        service.Create(opp_product);

                    }