visitor (0 QPoints)
  • FR
  • EN
  • NL
  • DE
  • ES
315 experts, 1193 registered users, 1659 questions already answered
European Experts Exchange, the very best site for high-quality IT solutions

New Improved Search!

 


05/10/2011 1h30 : Steve Jobs is dead, the father of Apple ][ is gone, we are all orphaned.

Databases :: MySql :: Value that occurs most Often
By: Squibi U.S.A.  Date: 04/06/2003 00:00:00  English  Points: 50 Status: Answered
Quality : Excellent
Hi,

How do I obtain the value that occurs most often for a specific group?

For example If I have a table as follows:

id - int
location - varchar
smoker - int

So a smoker is indicated by a 1. And locations could be anywhere. How would I find out which location has the highest level of smokers?

This is using mysql 3.23 so subselects are not possible. And I can't upgrade.

Any help appreciated.
By: monange Date: 04/06/2003 21:20:00 English  Type : Comment
Does this produce the correct result:

Select location, count(*)
from YourTable
where smoker = 1
group by location
limit 1

CHeers
By: VGR Date: 04/06/2003 21:24:00 English  Type : Answer
not easy at all.

I recommend a simple front-end (PHP) script, like this algorithm :

<?php
// initialize results structure
$locations=array();
$i=0; // counter of locations found
// initialize DB access
$connection1=mysql_connect($dbHost,$dbuser,$dbPassword) or die('could not connect1');
$connection2=mysql_connect($dbHost,$dbuser,$dbPassword) or die('could not connect2');
mysql_select_db($dbname,$connection1) or die('could not select DB1');
mysql_select_db($dbname,$connection2) or die('could not select DB2');
$yourtable='test'; // change this!

$query="SELECT DISTINCT location FROM $yourtable;";
// exec query on connection1
$result=mysql_query($query,$connection1) or die('invalid query '$query' : ".mysql_error());
// process results
while ($res=mysql_fetch_array($result)) {
$i++; // counter
// memorize location
$locations[$i]['location']=$res['location'];
// for this location, let's count occurences
$query="SELECT SUM(smoker) AS a FROM $yourtable WHERE location='{$res['location']}';";
// exec query on connection2
$result2=mysql_query($query,$connection2) or die('invalid query '$query' : ".mysql_error());
$res2=mysql_fetch_array($result2);
$nbsmokers=$res2['a'];
// memorize smokers
$locations[$i]['smokers']=$nbsmokers;
} // while locations found
// on exit, you've $i valid locations with data in $locations[0..$i]['location' | 'smokers']
?>

Do register to be able to answer

©2010 These pages are served without commercial sponsorship. (No popup ads, etc...). Bandwidth abuse increases hosting cost forcing sponsorship or shutdown. This server aggressively defends against automated copying for any reason including offline viewing, duplication, etc... Please respect this requirement and DO NOT RIP THIS SITE.
Please DO link to this page! Post to Twitter Post to Plurk Post to Yahoo Buzz Post to Delicious Post to Digg Post to Facebook Post to MySpace Post to Ping.fm Post to Reddit Post to StumbleUpon

EContact
browser fav
page generated in 90.853930 milliseconds

Why Google AdSense ads ?
compteur
 Ranking-Hits PageRank for this page