Jag e nybörjare på php och vill ha hjälp

skulle denna kod funka tror ni???

<?

switch($do){ 

case('add'):
 include "settings.php";
$ip = getenv("REMOTE_ADDR"); 
mysql_query("INSERT INTO gb (rubrik,namn,meddelande,datum,ip) VALUES ('$rubrik','$namn','$meddelande', now(),'$ip')"); 

mysql_close($db);

header("location:gastbok.php?do=show");

break;

case('show'):

include "settings.php";
$SQL = mysql_query("select * from gb order by datum desc ");
while($gb=mysql_fetch_array($SQL)){

echo $gb["rubrik"]; 
echo $gb["datum"];
echo $gb["namn"]; 
echo $gb["meddelande"];
echo $gb["ip"];
}
mysql_close($db);

echo ("<a href=gastbok.php?do=skriv>Skriv nytt inlägg</a>")

break;

case('new'):
	?>

<FORM METHOD=POST ACTION="gastbok.php?do=add">

<TABLE>
<TR>
	<TD>Rubrik:</TD>
	<TD><INPUT TYPE="text" NAME="rubrik"></TD>
</TR>
<TR>
	<TD>Namn:</TD>
	<TD><INPUT TYPE="text" NAME="namn"></TD>
</TR>
<TR>
	<TD>Meddelande</TD>
	<TD><INPUT TYPE="text" NAME="meddelande"></TD>
</TR>
<TR>
	<TD></TD>
	<TD><INPUT TYPE="submit"></TD>
</TR>
</TABLE>
</FORM>

	<?
break;

include "settings.php";
$SQL = mysql_query("select * from gb order by datum desc ");
while($gb=mysql_fetch_array($SQL)){

echo $gb["rubrik"]; 
echo $gb["datum"];
echo $gb["namn"]; 
echo $gb["meddelande"];
echo $gb["ip"];
}
mysql_close($db);

echo ("<a href=gastbok.php?do=skriv>Skriv nytt inlägg</a>")

}
?>