Reverse engineering output of a query

Question

The query below is able to track changes i two tables by detecting changes by colun row by row. I woul like to reengineer the query to look like the desired output.
select
HOUSE_KEY,
LOW,
HIGH,
count(src1) TBL_CURRENT, count(src2) TBL_STAGE
from
( select a.*,
1 src1,
to_number(null) src2
from TBL_CURRENT a
union all
select b.*,
to_number(null) src1,
2 src2
from TBL_STAGE b
group by
HOUSE_KEY,
LOW,
HIGH
having count(src1) <> count(src2);
Current Output
<pre>
HOUSE_KEY LOW HIGH TBL_CURRENT TBL_STAGE
1346553     23945076     97886375 0     1
1346569     06388286     7888258     0     1
1346569     06388286     78882515     1     0
1346553     23945077     97886368     1     0
</pre>
Desired Output
How can I make the query to look have the columns like this by extracting the column name and separating the value by comma in a single column?
<pre>
HOUSE_KEY          Column_chg     Value_prev     Value_new     Chg_column_count
1346553     low,HIGH     23945076, 97886375 945077,97886368 2
1346569     HIGH      7888258 78882515 1
</pre>
Edited by: CrackerJack on Feb 26, 2013 3:38 AM

Answer 1

with data (HOUSE_KEY,LOW,HIGH,TBL_CURRENT,TBL_STAGE) as (
select 1346553,23945076,97886375,0,1 from dual union all
select 1346569,06388286,7888258,0,1 from dual union all
select 1346569,06388286,78882515,1,0 from dual union all
select 1346553,23945077,97886368,1,0 from dual
select
house_key
,trim(both ',' from column_chg) column_chg
,trim(both ',' from value_prv) value_prv
,trim(both ',' from value_new) value_new
,decode(instr(trim(both ',' from column_chg),','),0,1,2) Chg_column_count
from (
select
house_key
,case when
lead(low) over (partition by house_key order by tbl_current)
!= low
then 'low,'
end
||
case when
lead(high) over (partition by house_key order by tbl_current)
!= high
then 'HIGH'
end column_chg
,case when
lead(low) over (partition by house_key order by tbl_current)
!= low
then low||','
end
||
case when
lead(high) over (partition by house_key order by tbl_current)
!= high
then HIGH
end value_prv
,case when
lead(low) over (partition by house_key order by tbl_current)
!= low
then lead(low) over (partition by house_key order by tbl_current)||','
end
||
case when
lead(high) over (partition by house_key order by tbl_current)
!= high
then lead(high) over (partition by house_key order by tbl_current)
end value_new
from
data
where column_chg is not null
HOUSE_KEY     COLUMN_CHG     VALUE_PRV     VALUE_NEW     CHG_COLUMN_COUNT
1346553     low,HIGH     23945076,97886375     23945077,97886368     2
1346569     HIGH     7888258     78882515     1