Dyanmic drop down-change drop down value

phprock

hi.. I am desparately lookin for tutorial or code that does the following ..

you have two drop down list. Changes on the first drop down it changes value on second drop down as well.

So, basick..i have list city in the first drop list and second drop down list i i have suburb list.. And these suburb list should change accroding t it's city..

Here is my code so far

<?
include "db.php"
global $link;

$result=mysql_query("select * from city ",$link);

echo"<select name=city_id onchange=suburb(this)>"; 
while($row=mysql_fetch_array($result)) 
{
 echo"<option value=$row[city_id]>$row[city_name]</option>";

}
echo"</select>";

function suburb()
{
global $link;
$result=mysql_query("select * from suburb where city='city_id'",$link);
echo"<select name=sub_id>";
while($row=mysql_fetch_array($result))
 {
 echo"<option value=$row[sub_id]>$row[sub_name]</option>";

 }

echo"</select>"; 

}

?>

Any help will be greatfull..

Regards

lobobr

The only way to do this with PHP is putting the "suburb" box on another frame or even an IFRAME, because PHP is processed in the server side. :eek: Terrible thing to do, I know...

A "no-reload" solution would be using JavaScript's innerHTML capabilities, but it will suck if you're expecting to work with a large amount of data... :rolleyes:

If you're interested in this JS solution, don't hesitate to send me an e-mail. I'll be glad to send you an example.

Best regards,

phprock

Thank you for the reply.. can u post the javascript solution here so other people might get benfefit from this code.

I did not find way to email you..

Regards

feldon23

First, your dropdown menus should probably be in a separate form from any larger form you may be having the user submit.

Second, the method that I use is Javascript, which reloads the entire page when you select something from one of the dropdown menus. If the user has partially filled in the form and then changes a menu item, this could be a problem.

The key is add some javascript to the SELECT dropdown menu item in your form like so, assuming the name of this menu is 'dropdown1':

Now when the user selects an item in this menu, the entire page will reload and, if you are using the GET method, the selected item will come in as $HTTP_GET_VARS['dropdown1'].

When you are displaying dropdown1, you should have a loop with if statements, if the item you are adding = $HTTP_GET_VARS['dropdown1'] then set that item to SELECTED.

And you could have it so if !isset($HTTP_GET_VARS['dropdown1']) then you can suppress the display of dropdown2.