在sql查询中逐个增加php变量

I have a table. The table have id, name and sname columns. I want to run a sql query in php. For example my query is

Select * from mytable where id=$n;

Here $n is a variable first value is 1. When the page is loaded this query is running. I listed a table query result. I want to increase $n value with a html button. The button is clicked $n value must be 2 and query must execute with new $n variable.

You can post with a form and increment the id

<?php
if (isset($_GET["increment"]) && $_GET["increment"] == 1)
   $n++;

$sql = "Select * from mytable where id=$n;";

// display data as usual

?>

<form>
    <input type="hidden" name="increment" value="1"/>
    <button type="submit">increment</button>
</form>

Use Javascript to make an Ajax request instead.

On each click of the button increment some Javascript variable. This variable can be passed to the script via AJAX.