There are lots of methods to flatten a table. You can cursor at it (loop or use a cte, temp table and build your string), but t-sql is a language of sets and anytime you move away from groups or sets you fitting a round peg in a square hole. Performance will hurt.
Specifically I wanted to comma separate out a table from something like this
orderid name
1 bob
1 mary
1 genie
2 billy
2 frank
2 grace
to something like this
orderid name
1 bob, mary, genie
2 billy, frank grace
If you are in 2005 or 2008 try the for xml command. A good example can be found by blaksheep here.
If you are in 2008 try on a little RANK.
If you are in 2000
you can use a function
see http://ryanfarley.com/blog/archive/2005/02/17/1712.aspx
