queryExpression

 QueryExpression query = new QueryExpression("demo_supplierconfiguration");
                query.ColumnSet = new ColumnSet() { AllColumns = false };
                query.ColumnSet.AddColumns("demo_supplierid", "demo_stationid", "demo_commodityid");
                query.Criteria = new FilterExpression() { FilterOperator = LogicalOperator.And };              
                query.Criteria.Conditions.Add(new ConditionExpression("demo_supplierconfigurationid", ConditionOperator.Equal, preImage.GetAttributeValue<EntityReference>("demo_configurationid").Id));
                EntityCollection collection = service.RetrieveMultiple(query);
                if(collection.Entities.Count > 0)
                {
                    Entity config = collection.Entities[0];

                    supplierId = config.GetAttributeValue<EntityReference>("demo_supplierid") != null ? config.GetAttributeValue<EntityReference>("demo_supplierid").Id : Guid.Empty;
                    stationId = config.GetAttributeValue<EntityReference>("demo_stationid") != null ? config.GetAttributeValue<EntityReference>("demo_stationid").Id : Guid.Empty;
                    commodityId = config.GetAttributeValue<EntityReference>("demo_commodityid") != null ? config.GetAttributeValue<EntityReference>("demo_commodityid").Id : Guid.Empty;


foreach (var items in result.Entities)
        {
            string date = items.GetAttributeValue<DateTime>("followupby").ToString();
            if (items.Attributes.Contains("customerid"))
            {
            string names = (items["customerid"] as EntityReference).Id.ToString();
            }
           // string Name = (items.Attributes["customerid"] as EntityReference).Id.ToString();

            string optional = items.FormattedValues["casetypecode"];
            string code = (items.FormattedValues.Contains("casetypecode") ? items.FormattedValues["casetypecode"] : "Ambiguous");
        }