If I understand correctly, you want the minimum distance (along with the stop_reference) for each service_id. If you didn't need the stop_reference, you could just do a GROUP BY:

-- not what you want
SELECT service_id, min(distance) FROM table
GROUP BY service_id;

[download]

But then you lose the stop_reference information, because you've "grouped" that away.

So what I'd probably do is use ORDER BY:

SELECT stop_reference, service_id, distance FROM table
ORDER BY service_id, distance;

[download]

Then you just print out (or store) every time the service_id changes:

my $last_service_id = -8675309;    # for a good time, call
while ($sth->fetch()) {
    if ($service != $last_service_id) {
        print "min dist for service '$service' = '$distance' at stop '
+$stops'\n";
        $last_service_id = $service;
    }
}

[download]

In reply to Re: Help with manipulating data from a database?? by ForgotPasswordAgain
in thread Help with manipulating data from a database?? by Harch84

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post, it's "PerlMonks-approved HTML":


  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.