PHP学习：php mysql_real_escape_string addslashes及mysql绑定参数防SQL注入攻击

$name=$_GET['name'];
$name=mysql_real_escape_string($name);
$sql="select *from table where name like '%$name%'";

SELECT * FROM table WHERE name LIKE '%41¿\\\' or sleep(10.10)=0 limit 1#%';

<?php
function check_input($value)
{
// 去除斜杠
if (get_magic_quotes_gpc())
 {
 $value = stripslashes($value);
 }
// 如果不是数字则加引号
/* http://www.manongjc.com/article/1242.html */
if (!is_numeric($value))
 {
 $value = "'" . mysql_real_escape_string($value) . "'";
 }
return $value;
}
$con = mysql_connect("localhost", "hello", "321");
if (!$con)
 {
 die('Could not connect: ' . mysql_error());
 }
// 进行安全的 SQL
mysql_set_charset('utf-8');
$user = check_input($_POST['user']);
$pwd = check_input($_POST['pwd']);
$sql = "SELECT * FROM users WHERE
user=$user AND password=$pwd";
mysql_query($sql);
mysql_close($con);
?>
 

echo addcslashes('foo[ ]','a..z'); //输出：foo[ ] 
$str="is your name o'reilly?"; //定义字符串,其中包括需要转义的字符 
echo addslashes($str); //输出经过转义的字符串

<?php  
$username = "aaa";  
$pwd = "pwd";  
$sql = "SELECT * FROM table WHERE username = ? AND pwd = ?";  
bindParam($sql, 1, $username, 'STRING'); //以字符串的形式.在第一个问号的地方绑定$username这个变量  
bindParam($sql, 2, $pwd, 'STRING');    //以字符串的形式.在第二个问号的地方绑定$pwd这个变量  
echo $sql;  
?>

<?php  
/**  
 * 模拟简单的绑定参数过程  
 *  
 * @param string $sql  SQL语句  
 * @param int $location 问号位置  
 * @param mixed $var   替换的变量  
 * @param string $type  替换的类型  
 */ 
$times = 0;  
//这里要注意,因为要“真正的"改变$sql的值,所以用引用传值 
function bindParam(&$sql, $location, $var, $type) {  
  global $times;  
  //确定类型  
  switch ($type) {  
    //字符串  
    default:          //默认使用字符串类型  
    case 'STRING' :  
      $var = addslashes($var); //转义  
      $var = "'".$var."'";   //加上单引号.SQL语句中字符串插入必须加单引号  
      break;  
    case 'INTEGER' :  
    case 'INT' :  
      $var = (int)$var;     //强制转换成int  
    //还可以增加更多类型..  
  }  
  //寻找问号的位置  
  for ($i=1, $pos = 0; $i<= $location; $i++) {  
    $pos = strpos($sql, '?', $pos+1);  
  }  
  //替换问号  
  $sql = substr($sql, 0, $pos) . $var . substr($sql, $pos + 1);  
}  
?>

<?php  
$times = 0;  
$username = "aaaa";  
$pwd = "123";  
$sql = "SELECT * FROM table WHERE username = ? AND pwd = ?";  
bindParam($sql, 1, $username, 'STRING'); //以字符串的形式.在第一个问号的地方绑定$username这个变量  
bindParam($sql, 2, $pwd, 'INT');    //以字符串的形式.在第二个问号的地方绑定$pwd这个变量  
echo $sql; //输出 SELECT * FROM table WHERE username = 'aaaa' AND pwd = 123  
?>

<?php  
$times = 0;  
$username = "aaa";  
$pwd = "fdsafda' or '1'='1";  
$sql = "SELECT * FROM table WHERE username = ? AND pwd = ?";  
bindParam($sql, 1, $username, 'STRING'); //以字符串的形式.在第一个问号的地方绑定$username这个变量  
bindParam($sql, 2, $pwd, 'STRING');    //以字符串的形式.在第二个问号的地方绑定$pwd这个变量  
echo $sql; //输出 SELECT * FROM table WHERE username = 'aaa' AND pwd = 'fdsafda\' or \'1\'=\'1'  
?>