php - Insert checkboxes into database -

** update **

i have updated code still no joy in getting join table update

i have 3 tables:

docs   doc_id   doc_name   doc_content cat   cat_id   cat_name   cat_color   cat_icon cat_doc_join   id   cat_id   doc_id 

i have ability create , insert data docs table, inserts doc_name , doc_content table fine. have introduced categories new_doc.php form shows array of categories available can selected via checkbox. stands unsure on how amend insert query take id of doc creating , id of selected checkboxes have selected , go on not insert docs table insert row(s) doc_cat_join table if 1 or more categories had been selected:

here script handles insert:

    <?php require ('../../db_con.php');      error_reporting(e_all);     ini_set('display_errors', '1');  // form validation & submission if ($_server['request_method'] == 'post') {      $errors = array(); // begin errors array      // check first name     if (empty($_post['doc_name'])) {         $errors[] = 'you forgot enter document name.';        } else {         $dn = mysqli_real_escape_string($dbc, trim($_post['doc_name']));     }      // check last name     if (empty($_post['doc_content'])) {         $errors[] = 'you forgot enter document content.';        } else {         $dc = mysqli_real_escape_string($dbc, trim($_post['doc_content']));     }      if (empty($errors)) {          // making query          $q = "insert docs (doc_name, doc_content, created_date) values ('$dn', '$dc', now() )";                    $r = mysqli_query($dbc, $q);          if ($r) {           $cat_ids=isset($_post['cats'])&&is_array($_post['cats'])?array_keys($_post['cats']):array();          $query='insert cat_doc_join (cat_id,doc_id) values';          $length=count($cat_ids);           for($i=0;$i<$length;$i++){              $query.='('.$cat_ids[$i].','.$doc_id.')';           if($i<$length-1)              $query.=',';           }          mysqli_query($dbc, $query);              // redirect document list             echo("<script>location.href = 'list_doc.php';</script>");          } else {              // error checking!             echo '<h1>system error!</h1> <p>you not registered because of system error!<br></p>';                           // debuggin message             echo '<p>' . mysqli_error($dbc) . '<br><br>query: ' . $q . '</p>';     }          mysqli_close($dbc);         exit();      } else {          // report errors         echo '<h1>error!</h1><p class="error">the following error(s) have occured:<br>';         foreach ($errors $msg) {             echo " - $msg<br>\n";         }         echo '</p><p>please try again!.</p><p><br></p>';      }  } ?> 

and here section of form array of categories:

<?php  $q = "select * cats";    $r = mysqli_query ($dbc, $q); // run query.  echo '<div class="view_body">';  // fetch , print records while ($row = mysqli_fetch_array($r)) { echo '<br><input type="checkbox" name="cats['.$row['cat_id'].']"> '.$row["cat_name"]. '</label>'; } echo '</div>';   ?> 

i guess seeking advice on how checkboxes can include value cat_id , within insert query add in join table insert too.

echo checkboxes this:

while ($row = mysqli_fetch_array($r)) {     echo '<br><input type="checkbox" name="cats['.$row['cat_id'].']"> '.$row["cat_name"]. '</label>'; } 

and use (i suppose $doc_id known, doc_id , cat_id ints , id field of cat_doc_join table autoincremented):

$cat_ids=isset($_post['cats'])&&is_array($_post['cats'])?array_keys($_post['cats']):array(); //please check fine here, ints, no sql injection,etc... $query='insert cat_doc_join (cat_id,doc_id) values'; $length=count($cat_ids); for($i=0;$i<$length;$i++){     $query.='('.$cat_ids[$i].','.$doc_id.')';     if($i<$length-1)       $query.=','; } //run query 

warning: you'll have sanitize input avoid sql injection , stuffs