<select id="b_id" name="b_id" class="form-control">
<?php
//$sql = "SELECT `id`,`Brand_name` FROM ".TBL_BRAND." WHERE 1 ORDER BY `id` ASC;";
$sql = "SELECT `id`,`Brand_name` FROM ".TBL_BRAND." WHERE 1 and `category_id`='".$cate_id."' ORDER BY `id` ASC;";
$query = mysqli_query($oconn, $sql);
while($row=mysqli_fetch_assoc($query)){
?>
<option value="<?=$row['id']?>"><?=$row['Brand_name']?></option>
<?php
}mysqli_free_result($query);
?>
</select>