Problem with counting rows

Hello,

I am very new to php, and need your help

I have 2 tables, one for main categories, and the other for sub categories

I am listing the main categories within 3 columns per each row like this:

Main Category 1 Main Category 2 Main Category 3
Main Category 4 Main Category 5 Main Category 6

Table Name: maincategories
Fields: id, main



And at the same time counting sub categories that belong to each main category

Table Name: subcategories
Fields: id, main_id, sub

I keep seeing this error:
Warning: mysql_result() [function.mysql-result]: Unable to jump to row 27 on MySQL result index 10

I can see the main category name, but can never see the sub category counts


this is the code:

   1. <?php
   2.                
   3. include "config.php";
   4.  
   5.                
   6.  
   7. $result = mysql_query("SELECT * FROM maincategories ORDER BY main") or die(mysql_error());
   8.  
   9. while ($row = mysql_fetch_array($result)) {
  10. $myvar = $row[id];
  11. $query = "SELECT main_id, COUNT(sub) FROM subcategories WHERE main_id = '$myvar' GROUP BY main_id";
  12.  
  13.  
  14.  
  15.  
  16.  
  17. $display_columns = 3;
  18. $count = mysql_numrows($result);
  19. $padding = ($display_columns-1)-(($count-1)%$display_columns);
  20.  
  21.  
  22. print "<table border='0' width='100%' cellspacing='0' cellpadding='0'>\n";
  23. for($i=0; $i<$count; $i++){
  24. if($i%$display_columns == 0)
  25.  
  26. print "<tr>\n";
  27. print "<td width=\"33%\">\n";
  28. $result2 = mysql_query($query) or die(mysql_error());
  29. while ($row = mysql_fetch_array($result2)){
  30. echo '<IMG SRC="images/icon.jpg" WIDTH="44" HEIGHT="44" border="0">
  31. <a href="category.php?category=' . mysql_result($result,$i,$main) . '"><strong>
  32. ' . mysql_result($result,$i,"main") . '' . mysql_result($result2,$myvar) . 'Sub Category
  33.  
  34. </strong></a>';
  35.  
  36. }
  37.  
  38. print "<p>&nbsp;</p>\n";
  39. print "</td>\n";
  40. if($i%$display_columns == $display_columns-1)
  41.  
  42. print "</tr>\n";
  43. }
  44.  
  45. if($padding!=0){
  46. for($i=0;$i<$padding;$i++)
  47. print "<td width=\"33%\"></td>\n";
  48. print "</tr>\n";
  49. }
  50.  
  51. print "</table>\n";
  52.  
  53.  
  54. }
  55.                
  56. mysql_close($link);
  57.                
  58. ?>

PHP:

Thank you in advance

 

This is only from a quick look, so forgive me if I'm mistaken, but I think the problem is in your loop setup.

In line 9 you are staring a WHILE loop for the main categories. So that goes around once per category.

Then in line 23 you start a FOR loop that is based on the number of main categories. That's inside the WHILE loop, so for each of the 6 categories it will loop 6 times.

As such, your $i count variable is getting to row numbers that don't exist, and when calling the mysql_result() function on non-existant rows it produces the error.

... I think.

-Ryan

 

thank you RJP, I think what you said makes sense
but I need the FOR loop to list the main categories in 3 columns method
do you have any idea about how to keep the listing method and counting the sub categories at the same time?