Sql (on Oracle) aging report by days

Question

I need help writing a aging report on oracle. The report should be like:

 aging file to submit total       17
 aging file to submit 0-2 days    3
 aging file to submit 2-4 days    4
 aging file to submit 4-6 days    4
 aging file to submit 6-8 days    2 
 aging file to submit 8-10 days   4

I can create a query for each section and then union all the the results like:

select 'aging file to submit total  ' || count(*) from FILES_TO_SUBMIT where trunc(DUE_DATE) > trunc(sysdate) -10
union all
select 'aging file to submit 0-2 days ' || count(*) from FILES_TO_SUBMIT where trunc(DUE_DATE) <= trunc(sysdate)  and trunc(DUE_DATE) >= trunc(sysdate-2)
union all
select 'aging file to submit 2-4 days ' || count(*) from FILES_TO_SUBMIT where trunc(DUE_DATE) <= trunc(sysdate-2) and trunc(DUE_DATE) >= trunc(sysdate-4) ;

I was wondering if there is a better way using oracle analytic functions or any other query that will get better performance?

Sample data:

CREATE TABLE files_to_submit(file_id int,   file_name varchar(255),due_date date); 

INSERT INTO FILES_TO_SUBMIT(FILE_ID,FILE_NAME,DUE_DATE) VALUES  ( 1, 'file_' || 1, sysdate);
INSERT INTO FILES_TO_SUBMIT(FILE_ID,FILE_NAME,DUE_DATE) VALUES  ( 2, 'file_' || 2, sysdate -5);
INSERT INTO FILES_TO_SUBMIT(FILE_ID,FILE_NAME,DUE_DATE) VALUES  ( 3, 'file_' || 3, sysdate -4);
INSERT INTO FILES_TO_SUBMIT(FILE_ID,FILE_NAME,DUE_DATE) VALUES  ( 4, 'file_' || 4, sysdate);
INSERT INTO FILES_TO_SUBMIT(FILE_ID,FILE_NAME,DUE_DATE) VALUES  ( 5, 'file_' || 5, sysdate-3);
INSERT INTO FILES_TO_SUBMIT(FILE_ID,FILE_NAME,DUE_DATE) VALUES  ( 6, 'file_' || 6, sysdate-7);
INSERT INTO FILES_TO_SUBMIT(FILE_ID,FILE_NAME,DUE_DATE) VALUES  ( 7, 'file_' || 7, sysdate-10);
INSERT INTO FILES_TO_SUBMIT(FILE_ID,FILE_NAME,DUE_DATE) VALUES  ( 8, 'file_' || 8, sysdate-12);
INSERT INTO FILES_TO_SUBMIT(FILE_ID,FILE_NAME,DUE_DATE) VALUES  ( 9, 'file_' || 9, sysdate-3);
INSERT INTO FILES_TO_SUBMIT(FILE_ID,FILE_NAME,DUE_DATE) VALUES  ( 10, 'file_' || 10, sysdate-5);
INSERT INTO FILES_TO_SUBMIT(FILE_ID,FILE_NAME,DUE_DATE) VALUES  ( 11, 'file_' || 11, sysdate-6);
INSERT INTO FILES_TO_SUBMIT(FILE_ID,FILE_NAME,DUE_DATE) VALUES  ( 12, 'file_' || 12, sysdate-7);
INSERT INTO FILES_TO_SUBMIT(FILE_ID,FILE_NAME,DUE_DATE) VALUES  ( 13, 'file_' || 13, sysdate-5);
INSERT INTO FILES_TO_SUBMIT(FILE_ID,FILE_NAME,DUE_DATE) VALUES  ( 14, 'file_' || 14, sysdate-4);
INSERT INTO FILES_TO_SUBMIT(FILE_ID,FILE_NAME,DUE_DATE) VALUES  ( 15, 'file_' || 15, sysdate-2);
INSERT INTO FILES_TO_SUBMIT(FILE_ID,FILE_NAME,DUE_DATE) VALUES  ( 16, 'file_' || 16, sysdate-6);
INSERT INTO FILES_TO_SUBMIT(FILE_ID,FILE_NAME,DUE_DATE) VALUES  ( 17, 'file_' || 17, sysdate-6);
INSERT INTO FILES_TO_SUBMIT(FILE_ID,FILE_NAME,DUE_DATE) VALUES  ( 18, 'file_' || 18, sysdate-5);
INSERT INTO FILES_TO_SUBMIT(FILE_ID,FILE_NAME,DUE_DATE) VALUES  ( 19, 'file_' || 19, sysdate-10);
INSERT INTO FILES_TO_SUBMIT(FILE_ID,FILE_NAME,DUE_DATE) VALUES  ( 20, 'file_' || 20, sysdate-9);


DROP TABLE files_to_submit;

Answer 1

Allow me to suggest WIDTH_BUCKET. This will divide the date range into equal size. Since you want 10 days range into groups of 2 days, the bucket size will be 10 / 2 = 5.

Query:

SELECT 
    CASE GROUPING(bucket) 
        WHEN 1 
            THEN 'aging file to submit Total' 
            ELSE 'aging file to submit ' || (bucket-1)*2 || '-' || (bucket)*2 || ' days'
    END             AS bucket_number, 
    COUNT(1)        AS files
FROM (
    SELECT 
        WIDTH_BUCKET(due_date, sysdate, sysdate-10, 5) bucket 
    FROM 
        files_to_submit
    WHERE 
        due_date >= sysdate-10
    )
GROUP BY
    ROLLUP(bucket)
ORDER BY
    bucket NULLS FIRST;

Result:

BUCKET_NUMBER                             FILES
------------------------------------ ----------
aging file to submit Total                   17
aging file to submit 0-2 days                 2
aging file to submit 2-4 days                 3
aging file to submit 4-6 days                 6
aging file to submit 6-8 days                 5
aging file to submit 8-10 days                1