SQL Help-How to achieve this?

Question

Hi,
I have the following query on Oracle 10g:
SELECT year, cargo, Balance_ThisYEAR, Balance_PreviousYear_categ, PCT, a.TERMINAL_ID
FROM (
SELECT /*+ ORDERED */
extract(year from b.rsrc_util_date) as year,
'CN' AS cargo,
ROUND(SUM(c.summary_units), 0) Balance_ThisYEAR,
Round(LAG(SUM(c.summary_units)) OVER(ORDER BY b.TERMINAL_ID, extract(year from b.rsrc_util_date)), 0) Balance_PreviousYear_categ,
ROUND((SUM(c.summary_units) - LAG(SUM(c.summary_units)) OVER(ORDER BY b.TERMINAL_ID, extract(year from b.rsrc_util_date)))/LAG(SUM(c.summary_units)) OVER(ORDER BY b.TERMINAL_ID, extract(year from b.rsrc_util_date)) * 100,1) AS "PCT",
b.TERMINAL_ID terminal_id
FROM ...
Results are:
Year Cargo ThisYear PrevYear Percentage TerminalID
1998     CN     835               NLP
1999     CN     1288     835     54.3     NLP
2000     CN     1209     1288     -6.1     NLP
2001     CN     4708     1209     289.5     NLP
2002     CN     2545     4708     -45.9     NLP
2003     CN     358     2545     -85.9     NLP
2004     CN     817     358     128.2     NLP
2005     CN     1222     817     49.6     NLP
2006     CN     618     1222     -49.4     NLP
2007     CN     766     618     23.9     NLP
2008     CN     702     766     -8.4     NLP
2009     CN     543     702     -22.6     NLP
2010     CN     332     543     -38.9     NLP
2003     AU     125               NLP
2004     AU     2     125     -98.4     NLP
2008     AU     12494     2     624600     NLP
2009     AU     6936     12494     -44.5     NLP
1998     ST     25125               NLP
1999     ST     214     25125     -99.1     NLP
2000     ST     228     214     6.6     NLP
2001     ST     1936     228     748.5     NLP
2002     ST     104     1936     -94.6     NLP
2003     ST     54     104     -48.1     NLP
2004     ST     16337     54     30153.7     NLP
2005     ST     18260     16337     11.8     NLP
2006     ST     4896     18260     -73.2     NLP
2007     ST     2494     4896     -49.1     NLP
2001     RO     516               NLP
2005     RO     10     516     -98.1     NLP
The result is fine as long as there is a value for cargo for the previous year but when there is no previous year value the % should be 100 and not as it shows.
Example:For Cargo AU Year 2008 as there is no year 2007 the query calculates it with respect to last year in the database i.e. 2004.It calculates like:12494-125/12494=624600
Is there a way to get a value like 100% instead of 624600 wherever there is no immediate previous year?
I would like something like:
2003     AU     125     0     0     NLP
2004     AU     2     125     -98.4     NLP
2008     AU     12494     *0     100*     NLP
2009     AU     6936     12494     -44.5     NLP
Any help in this regard will be highly appreciated.
Thanks
Edited by: user11401592 on Sep 28, 2010 9:14 AM

Answer 1

Give us some sample data to play with.
something like that should do it :with mytable as (
select 2003 year, 'AU' cargo, 125 summary_units, 'NLP' terminalid from dual
union all select 2004, 'AU', 2, 'NLP' from dual
union all select 2008, 'AU', 12494, 'NLP' from dual
union all select 2009, 'AU', 6936, 'NLP' from dual
union all select 2001, 'RO', 516, 'NLP' from dual
union all select 2005, 'RO', 10, 'NLP' from dual
select
        year,
        cargo,
        case
                when last_year is null or last_year!=(year-1) then cast(null as number)
                else last_summ
        end last_summ,
        curr_summ,
        case
                when last_year is null or last_year!=(year-1) then 100
                else trunc(100*v.curr_summ/v.last_summ,2)
        end pct,
        terminalid
from (
        select
        year,
        lag(year)
                over (partition by cargo, terminalid order by year) last_year,
        cargo,
        lag(summary_units)
                over (partition by cargo, terminalid order by year) last_summ,
        summary_units curr_summ,
        terminalid
        from mytable
) v;
      YEAR CA  LAST_SUMM  CURR_SUMM        PCT TER
      2003 AU                   125        100 NLP
      2004 AU        125          2        1,6 NLP
      2008 AU                 12494        100 NLP
      2009 AU      12494       6936      55,51 NLP
      2001 RO                   516        100 NLP
      2005 RO                    10        100 NLP
6 rows selected.