Revert Matrix table

Question

Hi All,
Some genius is causing me a major headache!
They create a table like the following:
part_number varchar2(50),
year varchar2(4),
jan_amount number,
feb_amount number,
mar_amount number,
apr_amount number,
may_amount number,
jun_amount number,
jul_amount number,
aug_amount number,
sep_amount number,
oct_amount number,
nov_amount number,
dec_amount number
This makes it extremely hard to report on
I would like to create a table like the following
part_number varchar2(50),
year varchar2(4),
month varchar2(3).
amount number
I am not sure how to write a query to transform the data for the matrix table into my new table. Could someone help with this? I would like to enter all the months for a year into the new table even if some of the month for that year are null. I will need to run this nightly......
Thanks so much !!

Answer 1

Hi,
832305 wrote:
Hi All,
Some genius is causing me a major headache!
They create a table like the following:
part_number varchar2(50),
year varchar2(4),
jan_amount number,
feb_amount number,
mar_amount number,
apr_amount number,
may_amount number,
jun_amount number,
jul_amount number,
aug_amount number,
sep_amount number,
oct_amount number,
nov_amount number,
dec_amount number
This makes it extremely hard to report on
I would like to create a table like the following
part_number varchar2(50),
year varchar2(4),
month varchar2(3).
amount number
I am not sure how to write a query to transform the data for the matrix table into my new table. Could someone help with this? I would like to enter all the months for a year into the new table even if some of the month for that year are null. I will need to run this nightly......
Thanks so much !!You're right; that's not a very good design.
Here's one way you can create a view like you requested:
CREATE OR REPLACE VIEW     normalized_x     AS
WITH   all_months       AS
     SELECT     TO_CHAR ( ADD_MONTHS ( SYSDATE
                         , LEVEL
               , 'MON'
               , 'NLS_DATE_LANGUAGE=ENGLISH'     -- If necessary
               )     AS month_abbr
     FROM     dual
     CONNECT BY     LEVEL     <= 12
SELECT     x.part_number
,     x.year
,     m.month_abbr
,     NVL ( CASE  m.month_abbr
               WHEN  'JAN'  THEN  x.jan_amount
                  WHEN  'FEB'  THEN  x.feb_amount
                  WHEN  'DEC'  THEN  x.dec_amount
           END
         , 0
         )     AS amount
FROM         table_x     x
CROSS JOIN  all_months     m
;If you don't want a view, the same technique will work in a CREATE TABLE AS statement, or an INSERT, or a plain query.
This will produce 12 rows of output for each row in the table, regardless of whether any (or all) of the 12 amount columns were NULL in the original table.
I hope this answers your question.
If not, post a little sample data (CREATE TABLE and INSERT statements, relevant columns only) for all tables, and also post the results you want from that data.
If you're asking about a DML statement, such as INSERT, the sample data will be the contents of the table(s) before the DML, and the results will be state of the changed table(s) when everything is finished.
Explain, using specific examples, how you get those results from that data.
Always say which version of Oracle you're using. The statement above will work in Oracle 9.1 and higher. Starting in Oracle 11.1, you could also use SELECT ... UNPIVOT, but I'm not sure that would be any more efficient or otherwise better in this case. ( Unpivot   is the generic term for taking multiple columns on one row, and displaying them as one column on multiple rows.)