<?php
//Mude aqui
$host = "localhost"; 
$user = "usuario do db";
$pass = "senha do db";
$banco = "nome do db";
$tab = "nome da tabela";

//Nao mude aqui
$db=mysql_connect("$host","$user","$pass");
mysql_select_db("$banco", $db);
$tabela = "select * from $tab";
$copiar=mysql_query($tabela, $db);
$abrir=fopen("arquivo2.txt","a+");
while($varia=mysql_fetch_row($copiar)) {
$limpar=fputs($abrir,implode(";",$varia));
}
fclose($abrir);
?>