Get all Account and Contact Entity Activities in MS CRM 4.0 through QueryExpression, LinkEntity and FilterExpression

Database Query: "SELECT * FROM ActivityPointerBase INNER JOIN ActivityPartyBase ON ActivityPartyBase.activityId = ActivityPointerBase.activityid WHERE ActivityPartyBase.partyobjecttypecode in (1,2)"
-- 1 for Account Entity and 2 for Contact Entity

static void GetAllContactandAccountActivities()

        {

            CRMHelper objCRMHelper = new CRMHelper();

            CrmService service = objCRMHelper.GetCRMService();

            AllColumns activityPointerBaseColumns = new AllColumns();

            QueryExpression query = new QueryExpression();

            query.ColumnSet = activityPointerBaseColumns;

            query.EntityName = EntityName.activitypointer.ToString();

            LinkEntity objLinkEntity = new LinkEntity();

            objLinkEntity.LinkFromEntityName = EntityName.activitypointer.ToString();

            objLinkEntity.LinkFromAttributeName = "activityid";

            objLinkEntity.LinkToEntityName = EntityName.activityparty.ToString();

            objLinkEntity.LinkToAttributeName = "activityid";

            //WHERE CONDITION

            FilterExpression activityFilter = new FilterExpression();

            ConditionExpression activityCondition = new ConditionExpression();

            activityCondition.AttributeName = "partyobjecttypecode";

            activityCondition.Operator = ConditionOperator.In;

            activityCondition.Values = new object[] { 1, 2 };

            activityFilter.Conditions = new ConditionExpression[] { activityCondition };

            objLinkEntity.LinkCriteria = activityFilter;

            // Link from ActivityPointer to ActivityPartyBase

            query.LinkEntities = new LinkEntity[] { objLinkEntity };

            BusinessEntityCollection result = service.RetrieveMultiple(query);

            if (result.BusinessEntities.Length > 0)

            {

                foreach (BusinessEntity objBE in result.BusinessEntities)

                {

                }

            }

        }