BBSを作ってみた。 

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Frameset//EN">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>Insert title here</title>
</head>
<body>
<form action="<?php echo $_SERVER["PHP_SELF"]?>" method="post">
	<table border="1">
		<tr>
			<td>お名前</td>
			<td><input type="text" name="g_name" size="30"></td>
		</tr>
		<tr>
			<td>メールアドレス</td>
			<td><input type="text" name="g_mail" size="30"></td>
		</tr>
		<tr>
			<td>メッセージ</td>
			<td><textarea row="5" cols="30" name="g_mes"></textarea></td>
		</tr>
		<tr>
			<td><input type="submit" value="送信"></td>
		</tr>
	</table>
</form>

<?php
$sv = "localhost";
$dbname ="guestbook";
$user = "root";
$pass = "mysql";

$conn = mysql_connect($sv, $user, $pass) or die("DB接続エラー");
mysql_select_db($dbname);

//書き込み処理
if ($_SERVER["REQUEST_METHOD"] == "POST") {
	$g_name = cnv_dbstr($_POST["g_name"]);
	$g_mail = cnv_dbstr($_POST["g_mail"]);
	$g_mes = cnv_dbstr($_POST["g_mes"]);

	if (!empty($g_name) and !empty($g_mes)) {
		$sql = "INSERT INTO guestdata(g_name, g_mail, g_mes, g_date)";
		$sql .= "VALUES(";
		$sql .= "'". $g_name ."',";
		$sql .= "'". $g_mail ."',";
		$sql .= "'". $g_mes ."',";
		$sql .= "'". date("Y/m/d H:i:s") ."')";

		$res = mysql_query($sql, $conn) or die("SQL実行エラー");
		if ($res) {
			echo "<p>書き込みありがとうございました。</p>";
		}
	}
} else {
	echo "<p>お名前かメッセージ欄が空欄です</p>";;
}

function cnv_dbstr($string) {
	$string = htmlspecialchars($string);

	if (get_magic_quotes_gpc()) {
		$string = stripslashes($string);
	}
	$string = mysql_real_escape_string($string);
	return $string;
}

//表示するためのスクリプト
$sql = "select * from guestdata order by id desc";
$res = mysql_query($sql, $conn) or die("データ抽出時エラー");

while ($row = mysql_fetch_array($res, MYSQL_ASSOC)) {
	echo "<hr>";
	if (!is_null($row["g_mail"])) {
		echo "<a href=\"mailto:" .$row["g_mail"]. "\">" . $row["g_name"] . "</a>";
	}else {
		echo $row[$g_name];
	}
	echo "(" . date("Y/m/d H:i" , strtotime($row["g_date"])) . ")";
	echo "<p>" .nl2br($row["g_mes"]) . "</p>";
}
?>
</body>
</html>