How to rename prefix all tables of the database, compatible with php 5.x and php 7.x

FOR PHP 5.x

 <?php

$db_server = "localhost";
$db_name = "vietpublic";
$db_username = "root";
$db_password = "vietpublic";

$old_prefix = "old_";
$new_prefix = "new_";

$session_id = mysql_connect( $db_server, $db_username, $db_password);
if (!$session_id) { die('Connection Failed: ' . mysql_error());}

$query = "SHOW TABLES FROM `" . $db_name . "`" . " LIKE '%" . $old_prefix . "%'";
$result = mysql_query ( $query, $session_id );
if (!$result) {die("Query Failed: " . mysql_error( $session_id ));}

while ( $row = mysql_fetch_array ($result) ) {
$old_table_name = $row[0];
$new_table_name = str_replace ($old_prefix, $new_prefix, $old_table_name);
$query = "RENAME TABLE `".$db_name."`.`".$old_table_name."`"." TO `".$db_name."`.`".$new_table_name."`";
if (mysql_query ( $query, $session_id )) {
echo "$old_table_name was renamed TO $new_table_name <br />";
} else {
echo "Error: $old_table_name was not renamed" . mysql_error( $session_id ) . "<br />";
}
}
mysql_close( $session_id );
?>

FOR PHP 7.x

 <?php
$db_server =     "localhost";
$db_name =         "vietpublic";
$db_username =     "root";
$db_password =     "";

$old_prefix =     "old_";
$new_prefix =     "new_";

$session_id = mysqli_connect( $db_server, $db_username, $db_password);
if (!$session_id) { die('Connection Failed: ' . mysql_error());}

$query = "SHOW TABLES FROM `" . $db_name . "`" . " LIKE '%" . $old_prefix . "%'";
$result = mysqli_query ($session_id, $query);
if (!$result) {die("Query Failed: " . mysql_error( $session_id ));}

while ( $row = mysqli_fetch_array ($result) ) {
    $old_table_name = $row[0];
    $new_table_name = str_replace ($old_prefix, $new_prefix, $old_table_name);
    $query = "RENAME TABLE `".$db_name."`.`".$old_table_name."`"." TO `".$db_name."`.`".$new_table_name."`";

        if (mysqli_query ($session_id, $query )) {
            echo "$old_table_name was renamed TO $new_table_name <br />";
        } else {
            echo "Error: $old_table_name was not renamed" . mysql_error( $session_id ) . "<br />";
        }
}

mysqli_close($session_id);
?>