PHP学习笔记_SESSION

<?php
// page1.php
/*create a new session if not find the SID
session_unset()  clear the variables of the session.
session_destroy() destroy the session completely .
session_encode() encode all variables in session then it can be stored in DataBase . or so have the session_decode() mehtod
*/
session_start();
echo 'Welcome to page #1  your session ID:'.session.id();

$_SESSION['favcolor'] = 'green';
$_SESSION['animal']   = 'cat';
//unset($_SESSTION['favcolor']);
$_SESSION['time']     = time();

// Works if session cookie was accepted
echo '<br /><a href="page2.php">page 2</a>';

// Or maybe pass along the session id, if needed
echo '<br /><a href="page2.php?' . SID . '">page 2</a>';
?>
After viewing page1.php, the second page page2.php will magically contain the session data. Read the session reference for information on propagating session ids as it, for example, explains what the constant SID is all about.

例子 2. A session example: page2.php
<?php
// page2.php

session_start();

echo 'Welcome to page #2<br />';

echo $_SESSION['favcolor']; // green
echo $_SESSION['animal'];   // cat
echo date('Y m d H:i:s', $_SESSION['time']);

// You may want to use SID here, like we did in page1.php
echo '<br /><a href="page1.php">page 1</a>';
?>

1. mysql_real_escape_string() 例子

<?php
$item = "Zak's and Derick's Laptop";
$escaped_item = mysql_real_escape_string($item);
printf ("Escaped string: %s\n", $escaped_item);
//tells how many rows are in this result set and if it equals one, does that mean the user's authenticated.
if(mysql_num_rows($result)==1)
?>
\ goes in front of the semicolon or single quote    It's pretty compelling
以上例子将产生如下输出：

Escaped string: Zak\'s and Derick\'s Laptop
sanity check 完整性 检查

isset -- 检测变量是否设置
bool isset ( mixed var [, mixed var [, ...]])

如果 var 存在则返回 TRUE，否则返回 FALSE。

如果已经使用 unset() 释放了一个变量之后，它将不再是 isset()。若使用 isset() 测试一个被设置成 NULL 的变量，将返回 FALSE。同时要注意的是一个 NULL 字节（"\0"）并不等同于 PHP 的 NULL 常数。

警告: isset() 只能用于变量，因为传递任何其它参数都将造成解析错误。若想检测常量是否已设置

显示出最近浏览的文章 mysqli : create table articles
<?php
$db = new mysqli("localhost","webuser","secret","corporate");

// '?' is a placeholder for the params
$stmt = $db->prepare("select id,title,content from articles where id = ?");

$stmt->bind_param('i',$_GET['id']);
//get data from the form : <form method="post" action="
//<?php echo $_SERVER['PHP_SELF'];>">
$stmt->execute();
$stmt->store_result();

if($stmt->num_rows == 1)
{
//将返回的结果集分别绑定到php变量中
$stmt->bind_result($id,$title,$content);

}
//添加文章标题并连接到列表
$articleLink = "<a href='article.php?id={$id}'>{$title}</a>"

if(! in_array($articleLink,$_SESSION['articles']))
$_SESSION['article'][] = $articleLink;

//显示文章
echo "<p>$title</p><p>$content</p>";

//显示请求文章列表
echo "<p>Recently Viewed Articles</p>";
echo "<ul>";
foreach($_SESSION['articles'] as $doc)
{
eho "<li>$doc</li>";
}
echo "</ul>";
?>

in_array()  -- 检查数组中是否存在某个值
<?php
$os = array ("Mac", "NT", "Irix", "Linux");
if (in_array ("Irix", $os)) {
print "Got Irix";
}
if (in_array ("mac", $os)) {
print "Got mac";
}
?>

mysql_fetch_assoc($result) //fetch associative array 获取关联数组