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Thread: About Intervals

  1. #1
    Join Date
    Dec 2003

    Unanswered: About Intervals


    Well, I'm having some problems with intervals. Maybe someone could help me.

    I'm using postgreSQL 7.3.3, Java and JfreeReport to deploy an application. Everythink is fine, but now I have a problem.

    To generate a report, a need to calculate some intervals. For example
    SELECT final_date - initial_date FROM someTable ;
    and that will give me the desired interval. But, when I try to get that interval in Java, I get this message "No class found for interval". I already asked at JFreeReport forum, and there, they told me it is possible a jdbc driver bug, but I'm using the latest jdbc driver for postgreSQL.

    They suggested me to cast the interval to a date type, and maybe that would work. But, I don't know if it is possible. I tried :

    SELECT date(final_date - initial_date) FROM someTable ; but I received this message: Bad date external representation '00:24'.

    Is there a way to cast an interval to a date ? or maybe someone know how to get an interval from a ResultSet from Java.

    Thanks for any help.
    Pablo Velasquez Rivas
    Computer Science Engineer - ITCR

  2. #2
    Join Date
    Feb 2004
    How about this?

    template1=# SELECT EXTRACT(epoch FROM ('Feb 16 2004 16:00'::timestamp - 'Feb 15 2004 15:00'::timestamp)::interval) AS secs;
    (1 row)
    As you can see, selecting the 'epoch' part of the interval will return the interval's representation in seconds. I presume you can take it from there.

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