PHP使用PDO实现mysql防注入功能详解

  <form action="test.php" method="post">
    姓名：<input name="username" type="text">
    密码：<input name="password" type="password">
    <input type="submit" value="登陆">
  </form>

<?php
  $username=$_POST["username"];
  $password=$_POST["password"];
  $age=$_POST["age"];
  //连接数据库，新建PDO对象
  $pdo=new PDO("mysql:host=localhost;dbname=phpdemo","root","1234");
  
  $sql="select * from login WHERE username='{$username}' AND password='{$password}' ";
  echo $sql;
  $stmt=$pdo->query($sql);
  //rowCount()方法返回结果条数或者受影响的行数
  if($stmt->rowCount()>0){ echo "登陆成功!"};

//通过quote方法,返回带引号的字符串，过滤调特殊字符
$username=$pdo->quote($username);
$sql="select * from login WHERE username={$username} AND password='{$password}' ";
echo $sql;
$stmt=$pdo->query($sql);
//rowCount()方法返回结果条数或者受影响的行数
if($stmt->rowCount()>0){
  echo "登陆成功！";
};

//通过占位符:username,:password传递值，防止注入
$sql="select * from login WHERE username=:username AND password=:password";
$stmt=$pdo->prepare($sql);
//通过statement对象执行查询语句，并以数组的形式赋值给查询语句中的占位符
$stmt->execute(array(':username'=>$username,':password'=>$password));
echo $stmt->rowCount();

//占位符为？
$sql="select * from login WHERE username=? AND password=?";
$stmt=$pdo->prepare($sql);
//数组中参数的顺序与查询语句中问号的顺序必须相同
$stmt->execute(array($username,$password));
echo $stmt->rowCount();

$sql="insert login(username,password,upic,mail) values(:username,:password,:age,:mail)";
$stmt=$pdo->prepare($sql);
//第三个参数可以指定参数的类型PDO::PARAM_STR为字符串，PDO::PARAM_INT为整型数
$stmt->bindParam(":username",$username,PDO::PARAM_STR);
$stmt->bindParam(":password",$password,PDO::PARAM_STR);
$stmt->bindParam(":age",$age,PDO::PARAM_INT);
//使用bindValue()方法绑定一个定值
$stmt->bindValue(":mail",'default@qq.com');
$stmt->execute();
echo $stmt->rowCount();

$sql="insert login(username,password,mail) values(?,?,?)";//注意不是中文状态下的问号？ 
$stmt=$pdo->prepare($sql); //按照?的顺序绑定参数值 
$stmt->bindParam(1,$username); 
$stmt->bindParam(2,$password); 
$stmt->bindValue(3,'default@qq.com'); 
$stmt->execute(); 
echo $stmt->rowCount();

$sql='SELECT * FROM user';
$stmt=$pdo->prepare($sql);
$stmt->execute();
$stmt->bindColumn(2,$username);
$stmt->bindColumn(4,$email);
while($stmt->fetch(PDO::FETCH_BOUND)){
  echo '用户名：'.$username.",邮箱：".$email.'<hr/>';
}