mysql_num_rows : invalid argument

[jwk811]

[code] $id = session_id();

$ip = $_SERVER['REMOTE_ADDR'];

$sql = "SELECT FROM polls WHERE id = '$id' or ip = '$ip'";
$result = mysql_query($sql);

$rows = mysql_num_rows($result);
if($rows > 0){
echo "One vote per person, sorry";
}
else{
$vote = $_POST['rodent'];
$poll = "feed";
$sql = "INSERT INTO polls(id, ip, vote, poll, date) VALUES('$id', '$ip', '$vote', '$poll', NOW())";
$result = mysql_query($sql);
}[/code]
why am i getting that error?

[Balmung-San]

Change [code]$sql = "SELECT FROM polls WHERE id = '$id' or ip = '$ip'";[/code] to [code]$sql = "SELECT * FROM polls WHERE id = '$id' or ip = '$ip'";[/code]

[Jessica]

And to catch these errors earlier, do:
$result = mysql_query($sql) OR die(mysql_error());