<?php// I'm assuming that dropdown 1_1 is the first one, 1_2 is the second one and so on.// subcat_1_1_1 is the first checkbox in the first dropdown in the first of the three sections.// subcat_1_1_2 is the second checkbox in that dropdown and so on.$categories = array();// Just a little trick to make multiple variables on a single line$section_exists = $category_exists = $subcategory_exists = true;// While the array-key exists, this loop will run and collect all checkboxes// in the array called categoriesfor($w=1;$section_exists==true;$w++){ if($!array_key_exists('subcat_'.$w.'_1_1', $_POST) { $section_exists = false; } for($x=1;$category_exists==true;$x++) { if($!array_key_exists('subcat_1_'.$x.'_1', $_POST) { $category_exists = false; } for($y=1;$subcategory_exists==true;$y++) { if(!array_key_exists('subcat_1_'.$x.'_'.$y, $_POST) { $exists=false; } if($POST['subcat_1_'.$x.'_'.$y] == 'checked') { $categories[$w][$x][] = $i; } } }}// Now you have an array with all checkboxes, something like// $subcat[1][1][1] = The number of the first checked checkbox in the first category// $subcat[1][1][2] = The number of the second checked checkbox in the first category and so on.// $subcat[1][2][1] = The number of the first checked checkbox in the second category// $subcat[1][2][2] = The number of the second checked checkbox in the second category and so on.// $subcat[2][1][1] = The number of the first checked checkbox in the first category, second section// $subcat[2][1][2] = The number of the second checked checkbox in the first category, second section and so on.$key_exists = true;$subkey_exists = true;$strings = array();// Loops through and turns all categories' arrays into stringsfor($h=1;key_exists==true;$h++){ if(!array_key_exists('['.$h.'][1]', $categories) { $key_exists = false; } for($i=1;$subkey_exists==true;$i++) { if(!array_key_exists('['.$h.']['.$i.']', $categories) { $subkey_exists = false; } // This will turn the array into a string with all subcategories, separated by ;. // For example, 0;3;53 if subcategory 0, 3 and 53 are checked $strings[$h][$i] = implode(';', $categories[$h][$i]); }}// Now strings[] contains all the strings (like 1;3;5 and 3;5;7). Loop through the array:for($x=0;$x<sizeof($strings);$x++){ for($y=0;$y<sizeof($strings[$x]);$y++) { // *build a query using the string* // Echoing just for debugging or whatever. echo "INSERT into categories ('category', 'subcategories') VALUES ('".$x."', '".$y."')"; }}// Done.// Store that field in the DB and then when you want them into an array again, do:// $array = exlode(';', $string);?>