<?php
    (...)
    require("sql.php3.inc");
    Header("Content-type: text/plain");

    function mkCond($s) {
        $s = " metal=\"".$s."\"";
    }

    $metal = array("ag","au","ba","ca","cd","co",
                "cr","cu","fe","gd","hg","k","mg",
                "mn","mo","na","ni","pb","pt","v",
                "w","zn","sr");
    array_walk($metal,"mkCond");

    $condition = implode($metal," OR ");
    if ($showmetal=="y") {
        $fields = "source_id,metal";
    } else {
        $fields = "source_id";
    }
    $qstring = "select distinct $fields from site where ";
    $qstring .= $condition." order by source_id";
    $link = SQL_pconnect();
    (...)
?>