使用PHP在Dropdown框中设置先前选择的值

Question

So, what I'm trying to achieve that after the user hits submit, the dropdown retains the value that the user have chosen. This is my code for the dropdown, I understand that I have to selected = 'selected', but I couldn't figure out how it fits in my code.

if (mysqli_num_rows($result) > 0) {     // output data of each row
    while($row_branch = mysqli_fetch_array($result)) {
        $menu_branch .= "<option value='".$row_branch["0"]."'>" . 
        $row_branch["0"]. "</option>";
    }
} 
echo $menu_branch;

Answer 1

if i understand right:

 // $yourvalue is previous dropdown value

if (mysqli_num_rows($result) > 0) {
  // output data of each row
 while($row_branch = mysqli_fetch_array($result)) {
     if ($row_branch["0"] == $yourvalue)
         $selected = "selected";
     else 
         $selected = "";
     $menu_branch .= "<option value='".$row_branch["0"]."' $selected>" . 
     $row_branch["0"]. "</option>";
  }
}

echo $menu_branch;