Finding the Weekend dates if its starting day of the week

Question

Hello FOlks,
I have this requirement where if the sysdate is monday i need to get the Data from Friday until Sunday i.e. sysdate -3 to sysdate -1
Otherwise i need to get the previous day data. How can we acheieve that for below query based on created date??
select c.client_code,
e.created_date,
        c.client_name,
   from event_client_field ecf, event e, client c
  where e.event_id = ecf.event_id(+)
    and e.client_id = c.client_id
    and trunc(e.created_date)
   = trunc(sysdate - 1)Edited by: user11961230 on Feb 1, 2011 10:01 AM

Answer 1

Hi,
So, you want to do one thing if today is a Monday, and you want to do something else if today is not Monday.
That sounds like a job for CASE:
select c.client_code,
e.created_date,
        c.client_name,
   from event_client_field ecf, event e, client c
  where e.event_id = ecf.event_id(+)
    and e.client_id = c.client_id
--  Nothing above this line was changed; everything below was changed
    and e.created_date >= TRUNC (SYSDATE) - CASE  TO_CHAR ( SYSDATE
                                                           , 'DY'
                                     , 'NLS_LANGUAGE=ENGLISH'     -- If necessary
                                 WHEN  'MON' THEN  3
                                 WHEN  'SUN' THEN  2     -- If wanted
                                            ELSE  1
                             END
    AND e.created_date < TRUNC (SYSDATE)
;Whenever you have a condition, try to use the raw column from your table as one of the operands instead of expressions based on the column. That is, try to say
AND e,.created_date < ...   rather than
AND TRUNC (e.created_date) < ...   That way, the optimizer can use an index on e.created_date, and it could be much faster.