PDO 数据访问抽象层

Posted 2020-08-26

//PDO
//数据访问抽象层
<?php

//1.操作其它数据库
//2.事务功能
//3.防止SQL注入攻击

//造PDO对象
//$dsn = "mysql:dbname=mydb;host=localhost"; //数据源
//$pdo = new PDO($dsn,"root","123");

//写SQL语句
//$sql = "select * from nation";
//$sql = "insert into nation values(‘n077‘,‘数据‘)";

//执行,返回的是PDOStatement对象
//$a = $pdo->query($sql); //执行查询
//$a = $pdo->exec($sql); //执行其他语句

//var_dump($a);

//$arr = $attr->fetchAll(PDO::FETCH_BOTH);
//var_dump($arr);


//事务功能
//事务：能够控制语句同时成功同时失败，失败时可以回滚

$dsn = "mysql:dbname=mydb;host=localhost";        //数据库名称，服务器
$pdo = new PDO($dsn,"root","123");

//设置异常模式
$pdo->setAttribute(PDO::ATTR_ERRMODE,PDO::ERRMODE_EXCEPTION); 

try
{
    //开启事务
    $pdo ->beginTransaction(); 
    
    $sql1 = "insert into nation values(‘n080‘,‘是删‘)";
    $sql2 = "insert into nation values(‘n070‘,‘好几款‘)";
    $sql3 = "insert into nation values(‘n075‘,‘好几款‘)";
    
    $pdo->exec($sql1);
    $pdo->exec($sql2);
    $pdo->exec($sql3);               // 三个的执行成功是并的关系，否则出错。
   
    //提交
    $pdo->commit();
}
catch(Exception $e)
{
    //抓住try里面出现的错误，并且处理zv
    //echo $e->getMessage(); //获取异常信息
    
    //回滚
    $pdo->rollBack();
}
//final()
//{
    //最终执行，无论以上try代码有没有出错，都会执行
//}



?>

</body>

<?php

//预处理语句防止SQL注入
$dsn = "mysql:dbname=mydb;host=localhost";
$pdo = new PDO($dsn,"root","123");

//$code = "n005";

//SQL语句里面需要加占位符 ?
//$sql = "select * from nation where code=?";
$sql = "insert into nation values(?,?)";

//准备执行,返回PDOStatement对象
$st = $pdo->prepare($sql);

//调用绑定参数的方法来绑定参数
//$st->bindParam(1,$code);
//$st->bindParam(2,$name);
//$name = "测试1";

//索引数组                      //注意区别
$attr = array("n006","测试2");

//执行方法
$st->execute($attr);

//$attr = $st->fetchAll();

//var_dump($attr);




?>

<?php

$dsn = "mysql:dbname=mydb;host=localhost";
$pdo = new PDO($dsn,"root","123");

//占位符是字符串
$sql = "insert into nation values(:code,:name)";

$st = $pdo->prepare($sql);      //等待执行。prepare准备
//$st->bindParam(":code",$code,PDO::PARAM_STR);
//$st->bindParam(":name",$name,PDO::PARAM_STR);
//$code = "n007";
//$name = "测试3";

//关联数组                               //与？占位符的区别
$attr = array("code"=>"n008","name"=>"测试4");

$st->execute($attr);


?>