php + sql: endless loop problem

konqi · 05-10-2008, 02:46 PM

What is wrong with this code? It gives an endless loop, but i don't see why.

Code:

<?php $sql = 'SELECT DISTINCT browser FROM stats';
      $query = mysql_query($sql);
      while ($browsers = mysql_fetch_assoc($query)) {
        $browser = $browsers['browser'];
        
        $sql = 'SELECT browser FROM stats WHERE browser="'.$browser.'"';
        $query = mysql_query($sql);
        $count = mysql_num_rows($query);
        $perc = $count / $visitors;
        echo $browser.' - '.$perc.'<br />';
      }
?>

thexplorer · 05-10-2008, 04:12 PM

Hi !

Maybe, you should use a different name in the loop for the $query variable
because each time you make a mysql_fetch_assoc passing $query variable, the variable content has been modified inside the loop.
Hope this will help you.

Jeff

konqi · 05-11-2008, 02:23 AM

Yes it worked, but i used this name throughout the hole document. Can i do this, or should i chose another name for each entry?

graemef · 05-11-2008, 02:51 AM

In the example that you gave the variable $query was used to assist with two tasks simultaneously. First the collection of the different browsers held on the stats table and then then to gather the number of rows there are on that table. Because you had used the same variable name for both tasks when it returned to the while condition it was looking at the reply from the second sql call not the first. That is why you need to have two distinct variable names.

graemef · 05-11-2008, 05:07 AM

A separate issue is that you can achieve what you want to do with a single SQL statement. I think that it will be something like this

Code:

SELECT browser count(*) FROM stats GROUP BY browser

konqi · 05-11-2008, 10:23 AM

what does 'group by' mean?

chrism01 · 05-11-2008, 05:43 PM

Read the manual: http://dev.mysql.com/doc/refman/5.0/en/select.html

graemef · 05-11-2008, 09:02 PM

The "group by" will sort the result into groups, when it is used with aggregate functions, in this case count(*) the result is to give you the value of all the elements in that group, so by grouping by browser you will get the count of all the rows for each specific browser.