Ii looks like this has been asked and answered in all the simple cases, excluding the one that i'm having trouble with. I've tried using a recursive CTE to generate this, however maybe a cursor would be better? or maybe a set of recursive functions will do the trick?

Can this be done in a cte?

consider the following table

PrimaryKey   ParentKey  
1            NULL       
2            1       
3            6
4            7
5            2
6            1
7            NULL

should yield

PK
1
-2
--5
-6
--3
7
-4

where the number of - marks equal the depth, my primary difficulty is the ordering.