How to replace url in .htaccess and get variable with GET request?

Question

PHP

Hello colleagues!
There is an interesting problem for me, but I am not at all familiar with .htaccess, please help me figure it out ...
The task is this:
There is an index.php page
How to get a variable in such site.ru/index.php?id=1 it’s clear how)))
and here is how to replace site.ru/index.php?id=1 with site.ru/user1 so that the script below, user 1 value accepts 1 as id value

<?php


if ($_GET['id'] = 1) {
    $id = 12346;
}
if ($_GET['id'] = 2) {
    $id = 12347;
}
if ($_GET['id'] = 3) {
    $id = 12348;
}

echo $id;

?>

Answer 1

RewriteEngine On
RewriteRule ^user([0-9]+)$ /index.php?id=$1 [L]