Using A Select Statement To Only Insert In Certain Rows

Hey,

I am not sure how to really explain this, but I'll give it a try.

I am looking to use a select statement in a way that I can tell it which rows to insert in depending on when only one result is returned. For example, if I run this statement:

SELECT Column1, Column2, Column3
FROM #Temp1

The result set is:

Column1---Column2---Column3
99--------6756756---55555
44--------55---------NULL

Column3 as only the one returned value, so I do not want it associated with any of the other rows, so I need this:

Column1---Column2---Column3
NULL------NULL------55555
99--------6756756---NULL
44--------55---------NULL

Another example:

The returned result now is:

Column1---Column2---Column3---Column4
99---------6756756---55555-----NULL
42---------55---------NULL------12345

So I need:

Column1---Column2----Column3----Column4
NULL-------NULL-------55555------NULL
NULL-------NULL-------NULL-------12345
99---------6756756----NULL-------NULL
44---------55----------NULL-------NULL


Does this make sense, and/or is it even possible?

I know it could be more of a presentation thing, but I would like to know how to do it in the code behind.

Thanks