for xml path example

gistfile1.sql

use tempdb;

IF OBJECT_ID('tempdb..#customerPreferences') IS NOT NULL
    DROP TABLE #customerPreferences

create table #customerPreferences ( username varchar(50), pref varchar(50) );

select * from #customerPreferences

insert into #customerPreferences ( username, pref )
select 'ryan', 'email'
union all
select 'ryan', 'phone'
union all
select 'ryan', 'fax'
union all
select 'shane', 'email'

select * from #customerPreferences


select distinct
	username
	, substring((SELECT
					',' + b.pref
                FROM #customerPreferences b
                WHERE a.username = b.username
				ORDER BY 
					b.pref ASC
					FOR XML PATH( '' )
					), 2, 1000 ) as prefs
from #customerPreferences a