Coalesce per row - get all Detail IDs grouped per HeaderRow e.g. Invoice1 | 1,2,3 Invoice 2 | 4,5,6

I have the following demo data (taken from Adventureworks) SalesOrderNumber SalesOrderDetailID SO43659 12 SO43659 11 SO43659 8 SO43659 9 SO43660 14 SO43660 13 SO43661 27 Is it possible to Group per SalesOrderNumber, and show the Detail IDs per SalesOrderNumber? SalesOrderNumber SalesOrderDetailID SO43659 12, 11, 8, 9 SO43660 14, 13 SO43661 27 http://www.sqlfiddle.com/#!3/7708b/1 What would be the best option for this please? Pivots? Cursors? Cursor which calls stored proc for each row , e.g. here ? Or this option from 4guysfromrolla which uses user-defined function? This is something that will be run once on only - at night - I dont need efficiency - just any help please.