我如何使用php通过id获取选择选项

Question

I want to access option of dropdowns by id using php like i have done in javascript .I want to do this work in php also.Is there any way to do this.Please guide.My JS code is.

var opt = amove.options[amove.selectedIndex];

   if(opt.id =="Exchange"){          
      document.getElementById('barcode2lb').style.display='block';

      document.getElementById('barcode2txt').style.display='block';
}
else{

     document.getElementById('barcode2lb').style.display='none';

     document.getElementById('barcode2txt').style.display='none';
}  

Answer 1

if you using raw php then

<select name="">
  <option value=""> select a option </option>
<?php
  $sql = 'SELECT * FROM table ORDER BY id ASC';
  $result_select = mysql_query($sql);
  $rows = array();
  while($row = mysql_fetch_array($result_select)){
    if($row['which column you want to compare'] == value){
      echo "<option value="".$row['value index']."">".$row['value index']." </option>"
   }
  }
?>

Answer 2

For example,

<select>
<?php foreach($yourArr as $row):
if(yourConidtion){
  $selected='selected';
}else{
  $selected='';
}?>
<option value="<?= $row->id?>" <?= $selected ?>><?= $row->name ?></option>
<?php endforeach;?>
</select>

I think this is what you asked for

Answer 3

PHP is a server side language therefore you will need your JS to post your id values using AJAX . Make an AJAX call from your JS code and handle the data in your PHP code