I want to query a list of items that is a dropdown according to a previous drop down

How do I query a drop down according to anoth开发者_StackOverflow中文版er queries result

so I have a function getMakes() that returns a list of vehicle makes that i have placed in a dropdown,

I created a new query in the function getModels() that gets all the possible models for every vehicle make, i want to make a where statement that only grabs the makes for the vehicle make that was selected

I was thinking to have the function getModels($make) where $make is the value we want in the where clause, but how do i make the value in the where clause dynamic?

You will need to use ajax or javascript if you want to have the second dropdown populate based on a selection from the first dropdown. You can't have PHP do the work in this case; PHP will run once when the page loads and that's it.

You can have your main controller:

function index(){
    $l1=$this->db->query('SELECT make FROM cars');
    $l1arr = Array();
    foreach($l1 as $key=>$value){
        $l1arr[$key]=$value;
    }
    $data['list1']=$l1arr;
    $this->load->view('welcome_message',$data);
}

then another controller that returns the models: [assuming you pass the make in the url]

function car_models(){
    $make = $this->uri->segment(2);//the make passed in URL e.g. site.com/getcars/honda
    $models=$this->db->query('SELECT models FROM cars WHERE make="',$make,'"');
    $marr = array();
    foreach($marr as $key=>$value){
        $marr[$key]=>$value;
    }
    return form_dropdown('models_dropdown',$marr);
}

then have an ajax function call the models page based on the initial selection; you can do it with jQuery like so:

function getModels(make){
    jQuery.ajax({
      type: 'GET',
      url: '/getcars/'+make,
      success: function(data){
          //populate dropdown with models
          jQuery('#models_dropdown').html(data);
      }
    });
    return false;
}         

not sure I got all the details correct, but this should at least point you in the right direction.

Couldn't you make the $sql string use some string concatenation to produce the SQL query? There should be some checking to prevent a SQL injection attack as doing this can be a little risky from a security perspective.

PHP string concatenation would be a tutorial if you want some more help with that.