Dropdown menu not saying No

I have the following controller that works fine if "yes" is selected but is causing me some trouble if "no" is selected.

How could I make it insert "no" into the db?**

** I have added the elseif in trying to get it to say NO!

Controller:

//Dropdown Placeholder
        $dropdown = $this->input->post('add_fields_placeholder', TRUE);
        $dropdown = '';

        if($dropdown = 'yes')
        {
          $dropdown_value = $this->input->post('add_fields_placeholderValue', TRUE);
        }else($dropdown = 'no')
        {
        }

View:

<label for="add_fields_placeholder">Placeholder: </label>
    <select name="add_fields_placeholder" id="add_fields_placeholder">
        <option value="">Please Select</option>
        <option value="yes" <?php echo set_select('add_fields_placeholder','yes', ( !empty($placeholderType) && $placeholderType == "yes" ? TRUE : FALSE ));?>>Yes</option>
        <option value="no" <?php echo set_select('add_fields_placeholder','no', ( !empty($placeholderType) && $placeholderType == "no" ? TRUE : FALSE ));?>>No</option>
    </select>

Okay, first of all get rid of

$dropdown = '';

Because this resets your value, so it won't hold yes or no

Secondly, both

if($dropdown = 'yes')
else($dropdown = 'no')

Need to use == instead of =. = is used to asign a value to a variable, == is used to compare values.

Does it work after you've made those changed?

Edit: You can't use else, and then add another condition. You either need to just use

else { 

or use else

if($dropdown == 'no') {

Edit: For clarity and information, what you're doing in your if's with the single = is not asking if it's equal to yes or no, you're making it equal, and asking if you were able to