Find rows from a table with no Activities

Question

Hi,
I have a ‘Data’ table in relation with a ‘Note’ table with a date and I would like to find all the rows in the ‘Data’ table that do not have any ‘Note’ taken in the the last 3 months (including no ‘Note’ at all)?
THanks,

Answer 1

Hi,
934281 wrote:
Thanks for the great and quick answers!
Could someone tell me what is the difference between the 2 methodes (Not Exist vs Not In)?They can usually be used to get the same results. Sometimes, it's easier to understand the logic of one rather than the other. Use whichever one you prefer. I can't guarantee that the optimizer won't do exactly the same thing, regardless of which one you use.
Also, I would I add in the Select the Date of the most recent Note and sort ASC so that I could have the Data that had not activity in the last 3 months and sorted by the one that had no activity the longest time ago first?In that case, I suggest a join, rather than either EXISTS or IN:
WITH     got_r_num     AS
     SELECT     d.*
     ,     n.notedate
     ,     ROW_NUMBER () OVER ( PARTITION BY  d.id
                               ORDER BY          n.notedate     DESC     NULLS LAST
                       )         AS r_num
     FROM           data        d
     LEFT OUTER JOIN      note        n  ON  n.dataid     = d.id
SELECT       *     -- Or list all couumns except r_num
FROM       got_r_num
WHERE       r_num          = 1
AND       NVL ( notedate
           , SYSDATE - 99     -- or any date more than 3 months ago
           ) <  ADD_MONTHS ( SYSDATE
                              , -3
ORDER BY  notedate
;If you'd care to post some sample data (CREATE TABLE and INSERT statements), and the results you want from that data, then I could test this.
When you say you don't want dates within the last 3 months, I assume you're including dates in the future. (Future dates may be impossible in your table, anyway.)
3 months can be as short as 89 days or as long as 92 days. I used ADD_MONTHS (sysdate, -3) to get exactly 3 months; you can use SYSDATE - 90 if that suits your needs.