Simple script to copy by id from one to another db table

db_copy.php

<?php

$con = mysqli_connect("host","user", "password");

mysqli_select_db($con, "dbname");

$stepSize = 100000;
foreach(range(1,50000000, $stepSize) as $step){
    $sql = sprintf('insert into tmp_table select * from table where id >= %d and id < %d', $step, $step + $stepSize);
    mysqli_query($con, $sql);
    echo $sql .PHP_EOL;
}