/*
   connect to MySQL inside a MySQL function !
*/
mysql_connect ( "localhost", "root", "" );
mysql_select_db ( "mysql" );
$result = mysql_query ( "SELECT user FROM user" );
$RET="";

/*
   Returns all the rows in a string
*/
while ( $riga = mysql_fetch_row ( $result ) )
{
   $RET = $RET . $riga[0] . ";";
}
mysql_free_result ( $result );
mysql_close();