Group by Query not giving desired results

Question

Hi,
I've a requirement to find minimum month based on status:
The following query is giving error :
SELECT
          b.app_name,
          DECODE (a.status,
          'C','Closed',
          'O','Open',
          'F','Future',
          'W','Pending',
          'N','Not Opened') decode_status
          MIN(a.period_name)
FROM     table a,
     table b
WHERE     a.app_id     =     b.app_id
AND          b.app_name      =     'NAME1'
AND          a.book_id     =     &book_id
AND          a.status      =      'O'
GROUP BY      b.app_name,
          DECODE (a.status,
          'C','Closed',
          'O','Open',
          'F','Future',
          'W','Pending',
          'N','Not Opened') decode_status
for ex: in the above query if I've four records with status 'O' and period_name as 'May-12', 'Jun-12','Jul-12' ,'Aug-12' then I need to pick 'May'
Thanks,
Kiran

Answer 1

Hi, Kiran,
user518071 wrote:
Hi,
I've a requirement to find minimum month based on status:
The following query is giving error :
SELECT
          b.app_name,
          DECODE (a.status,
          'C','Closed',
          'O','Open',
          'F','Future',
          'W','Pending',
          'N','Not Opened') decode_status
          MIN(a.period_name)
FROM     table a,
     table b
WHERE     a.app_id     =     b.app_id
AND          b.app_name      =     'NAME1'
AND          a.book_id     =     &book_id
AND          a.status      =      'O'
GROUP BY      b.app_name,
          DECODE (a.status,
          'C','Closed',
          'O','Open',
          'F','Future',
          'W','Pending',
          'N','Not Opened') decode_status
for ex: in the above query if I've four records with status 'O' and period_name as 'May-12', 'Jun-12','Jul-12' ,'Aug-12' then I need to pick 'May'
Thanks,
KiranIt looks like you're almost there.
If period_name is a DATE, then
MIN (a.period_name)is finidng the earliest period name, such as 5 May 2012 17:03:49. If you just want to see 'May 2012', then change that to
TO_CHAR ( MIN (a.period_name)
        , 'Mon YYYY'
        )If a.period_name is a VARCHAR2, then change it to a DATE. The best way to do this is permanently. There is no reason to store date information in VARCHAR2 columns. Oracle supplies DATE columns; there's no extra cost for using them. DATE columns were designed for storing date information, use them to do that.
if you must keep your date information in VARCHAR2 a column, then use TO_DATE in the query. It will be slow, and you'll have run-time errors if any of the information is in the wrong format. That's what happens when you store date information in VARCHAR2 columns.
I hope this answers your question.
If not, post a little sample data (CREATE TABLE and INSERT statements, relevant columns only) for all tables involved, and also post the results you want from that data.
Explain, using specific examples, how you get those results from that data.
Always say which version of Oracle you're using.
See the forum FAQ {message:id=9360002}