I came up with this code:

selectPntKey,

RowNumber,

CASE

WHEN RowNumber = 1 THEN Qty

ELSE 0

ENDQty,

min(FromDate1),

max(ToDate1),

min(FromDate2),

max(ToDate2)

from

(

selectPntKey,

ROW_NUMBER() OVER(PARTITION BY PntKey ORDER BY PntKey) AS 'RowNumber',

Parent.PntQty Qty,

Child1.Cd1FromDate FromDate1,

Child1.Cd1ToDate ToDate1,

null FromDate2,

null ToDate2

FROM Parent

LEFT JOIN Child1 ON Child1.Cd1PntKey = Parent.PntKey

union

select PntKey,

ROW_NUMBER() OVER(PARTITION BY PntKey ORDER BY PntKey) AS 'RowNumber',

Parent.PntQty Qty,

null FromDate1,

null ToDate1,

Child2.Cd2FromDate FromDate2,

Child2.Cd2ToDate ToDate2

FROM Parent

LEFT JOIN Child2 ON Child2.Cd2PntKey = Parent.PntKey

) as work

group by PntKey,

RowNumber,

CASE

WHEN RowNumber = 1 THEN Qty

ELSE 0

END

And I get results like this:

PntKey RowNumber Qty FromDate1 ToDate1 FromDate2 ToDate2

----------- -------------------- ----------- ---------- ---------- ---------- ----------

1 1 100 2012-01-01 2012-02-01 2011-12-01 2011-12-31

1 2 0 2012-04-01 2012-05-01 NULL NULL

2 1 200 2012-01-15 2012-05-15 2012-01-01 2012-02-01

2 2 0 NULL NULL 2012-02-15 2012-05-15

3 1 300 2012-05-01 2012-07-01 2012-09-01 2012-10-01

Warning: Null value is eliminated by an aggregate or other SET operation.

(5 row(s) affected)