How to find out the rows inserted in the last n minutes ?

Question

Hi all,
I have a log table where, every time a warning is issued, a new row is added. The table has a field with the sysdate when the warning was issued.
I'd need to collect all warnings in the last (supposing) 30 minutes and send a mail to the administrator. Looking at some faqs I have elaborated this:
select * from PROCEDURE_LOGS p where ((p.DATE_LOG - sysdate)*-1440) < 30
However this does not produce anything.
Can anybody help me to correct this statement ?
Thanks a lot
Frank

Answer 1

Hi, Frank,
That looks okay to me. Are you sure you have rows in the table with a date_log in the last 30 minutes? Post some sample data (CREATE TABLE and INSERT statements), and the results you expect from that data for a given value of SYSDATE.
By the way, you can make the WHERE clause clearer like this:
select     *
from      PROCEDURE_LOGS     p
where      ( (sysdate - p.DATE_LOG)
     * 1440           -- = 24 * 60
     ) < 30but this won't change the results.
Edited by: Frank Kulash on Dec 1, 2010 9:51 AM
I just saw Toon's reply:
where     p.DATE_LOG > sysdate - (30 / 1440)as Toon suggested, is clearer still, and potentially more efficient if ther's an index on date_log.