PHP Tips -- Form

** get Multi-select data in a form

<tr>
<td valign="top">Area code:</td>
<td>
 <select id="area" name="area[]" size=6 multiple>
 //Use area[] for php to get more value
<script>
 frm = this.document.formname;
 frm.area.options[frm.area.length] = new Option("--", "", false, false);
</script>
<?php

 $id = @mysql_connect($host, $user,$dbpasswd) or
   ErrMsg("Cannot connect to MySQL server");
 @mysql_select_db($dbname,$id) or ErrMsg("Cannot open database");
 $query = "select * from area where id=$uid;";
 $result = mysql_query($query, $id);

 while ($uarray = mysql_fetch_array($result)){
  $area = $uarray["area"];
  echo "<option value='$area'>$area";
 }

 mysql_free_result($result);
 mysql_close($id);
?>
 </select>

</td>
</tr>

<?php
// Get Multi-select data in a form

foreach($_POST['area'] as $value){
 if ($value != ''){
  $query = "insert into area (uid, area) values($uid, '$value');";
  $result = mysql_query($query, $id) or ErrMsg("Query Error: $query");
 }
}


/* To get multi check in a form:
   Give the group of check box the same name, end with [],
   PHP compiles the user input for this field into an array.
*/
?> 
 <input type='checkbox' name="codes[]" value='aaa'>
 //Use codes[] for php to get more value as an array
 <input type='checkbox' name="codes[]" value='bbb'>
 //if didn't set value, php will get 'on' when checked
 //else php get the value when checked.
 //If unchecked, php get null no matter value is set.
 <input type='hidden' value='' name='codesarray'>

<script>
  function validate()
  {
 // Get checkbox array before submit
 codearray = document.Formname.elements['codes[]'];

 for (i=0; i {
   if (codearray[i].checked == true)
   {
  document.Formname.codesarray.value += codearray[i].value + ",";
   }
 }
  }
</script>

<?php
 if (!isset($_POST['codes']))
 {
  $codesarray = '';
 }else{
  // Get an array of codes
  $codes = $_POST['codes'];
  $codesStr = implode(",", $codes); // combine entries into a string
 }
 echo "\n";
?>