将存储的值从mysql绑定到组合框

I have the following php code

<select class="form-control" name="txtNakshatra">
<?php
 $query = "SELECT * FROM MasterTable;
 $result = mysqli_query($dbcon, $query);
 while ($row = mysqli_fetch_array($result)) {
  echo "<option value='" . $row['Id'] . "'>" . $row['Name'] . "</option>";
 }
?>
</select>

Which will Display all the details from the master table in a combo box.

Now I am inserting $row['Id'] into client Table. So In client table I have stored the particular row value.

Now when I open the same page, I need to display the stored value in the Combo box.

If I select master_table_value_1 from the listbox for the first time which will have the value as 15 . the next time when I load the page, I need to display master_table_value_1 in my Combo box.

How to do it? Any help appreciated