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

<?php
  $username=$_POST["username"];
  $password=$_POST["password"];
  $age=$_POST["age"];
  //連接數(shù)據(jù)庫(kù)，新建PDO對(duì)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($sql);
  //rowCount()方法返回結(jié)果條數(shù)或者受影響的行數(shù)
  if($stmt->rowCount()>0){ echo "登陸成功!"};

//通過quote方法,返回帶引號(hào)的字符串，過濾調(diào)特殊字符
$username=$pdo->quote($username);
$sql="select * from login WHERE username={$username} AND password='{$password}' ";
echo $sql;
$stmt=$pdo->query($sql);
//rowCount()方法返回結(jié)果條數(shù)或者受影響的行數(shù)
if($stmt->rowCount()>0){
  echo "登陸成功！";
};

//通過占位符:username,:password傳遞值，防止注入
$sql="select * from login WHERE username=:username AND password=:password";
$stmt=$pdo->prepare($sql);
//通過statement對(duì)象執(zhí)行查詢語(yǔ)句，并以數(shù)組的形式賦值給查詢語(yǔ)句中的占位符
$stmt->execute(array(':username'=>$username,':password'=>$password));
echo $stmt->rowCount();

//占位符為？
$sql="select * from login WHERE username=? AND password=?";
$stmt=$pdo->prepare($sql);
//數(shù)組中參數(shù)的順序與查詢語(yǔ)句中問號(hào)的順序必須相同
$stmt->execute(array($username,$password));
echo $stmt->rowCount();

$sql="insert login(username,password,upic,mail) values(:username,:password,:age,:mail)";
$stmt=$pdo->prepare($sql);
//第三個(gè)參數(shù)可以指定參數(shù)的類型PDO::PARAM_STR為字符串，PDO::PARAM_INT為整型數(shù)
$stmt->bindParam(":username",$username,PDO::PARAM_STR);
$stmt->bindParam(":password",$password,PDO::PARAM_STR);
$stmt->bindParam(":age",$age,PDO::PARAM_INT);
//使用bindValue()方法綁定一個(gè)定值
$stmt->bindValue(":mail",'default@qq.com');
$stmt->execute();
echo $stmt->rowCount();

$sql="insert login(username,password,mail) values(?,?,?)";//注意不是中文狀態(tài)下的問號(hào)？ 
$stmt=$pdo->prepare($sql); //按照?的順序綁定參數(shù)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($stmt->fetch(PDO::FETCH_BOUND)){
  echo '用戶名：'.$username.",郵箱：".$email.'<hr/>';
}