Pomoc s MySQL

potreboval by poradi s timto
<?
$spojeni=mysql_connect("xxx","xxx","xxx");
$co="SELECT * FROM adresar";
$navrat=mysql_db_query("mydata", $co, $spojeni);
echo("<table border=\"1\">");
for ($i=0;$i<mysql_num_fields($navrat); $i++){
echo("<td><strong>".mysql_field_name($navrat, $i)."</strong></td>");
}
while (list($jmeno) = mysql_fetch_row($navrat)){
echo("<tr><td>$jmeno</td></tr>");
}
echo("</table>");
?>

Melo by to vypsat jmena z databaze ale pise to tohle:
Warning: mysql_num_fields(): supplied argument is not a valid MySQL result
resource in /3w/wz.cz/m/magnetradio/djspage/zobrazreg.htm on line 8

Warning: mysql_fetch_row(): supplied argument is not a valid MySQL result
resource in /3w/wz.cz/m/magnetradio/djspage/zobrazreg.htm on line 11
Moc tomu nerozumim takze bych potreboval pomoct. diky