Get fetch XML link-entity attributes using C# in Dynamics CRM 2011

Following example code shows how to get Account Primary Contact details using fetch XML link-entity

Note: Specify ‘alias’ name different than ‘attributename’ and use same alias name in GetAttributeValue

        //Get Account PrimaryContact details
        public static void GetAccountPrimaryContactDetails(Guid accountId, IOrganizationService orgService)
        {
            var contactFirstName = default(object);
            var contactLastName = default(object);
            var contactFullName = default(object);

            string fetchXML = string.Format(@"<fetch version='1.0' output-format='xml-platform' no-lock='true' mapping='logical'>
                                                <entity name='account'>
                                                    <attribute name='name' />                                                                                
                                                    <filter type='and'>
                                                        <condition attribute='statuscode' operator='eq' value='1' />                                            
                                                        <condition attribute='accountid' operator='eq' value='{0}' />
                                                    </filter>                                        
                                                    <link-entity name='contact' from='contactid' to='primarycontactid' alias='ab'>
                                                         <attribute name='fullname' alias='as_fullname' />
                                                         <attribute name='firstname' alias='as_firstname' />                                             
											             <attribute name='lastname' alias='as_lastname' />
                                                    </link-entity>
                                                </entity>
                                            </fetch>", accountId.ToString());

            var fetchExp = new FetchExpression(fetchXML);

            EntityCollection accountEntity = orgService.RetrieveMultiple(fetchExp);

            if (accountEntity.Entities.Count > 0)
            {
                //Primary Contact Fullname
                AliasedValue avContactFullname = accountEntity.Entities[0].GetAttributeValue<AliasedValue>("as_fullname");
                if (avContactFullname != null)
                    contactFullName = avContactFullname.Value;
                //Primary Contact Firstname
                AliasedValue avContactFirstname = accountEntity.Entities[0].GetAttributeValue<AliasedValue>("as_firstname");
                if (avContactFirstname != null)
                    contactFirstName = avContactFirstname.Value;
                //Primary Contact Lastname
                AliasedValue avContactLastname = accountEntity.Entities[0].GetAttributeValue<AliasedValue>("as_lastname");
                if (avContactLastname != null)
                    contactLastName = avContactLastname.Value;
            }
        }