PHP 数据对象 （PDO） 扩展为PHP访问数据库定义了一个轻量级的一致接口。
<?php try { $dsn = "mysql:host=localhost; port=3306; dbname=wsq_hotel; charset=utf-8"; $user = 'root'; $psw ='root'; $pdo = new PDO($dsn,$user,$psw); $sql = 'select goods_prices from wsq_goods_info where goods_id=2'; // $sql = "show database"; $res = $pdo->query($sql) or var_dump($pdo->errorInfo()); // var_dump($res); $mon = $res->fetch(PDO::FETCH_ASSOC); echo $mon['goods_price']; } catch (PDOException $e) { echo $e->getMessage(); } ?>
PDO操作事务
//开启事务 beginTransacition() //回滚 rollback() //提交 commit() //判断是否处于事务之中 inTransaction()
返回最后插入行的ID
PDO::lastInsertID()
exec()执行
与query()相比，exec()返回的是受影响行数
$sql = "insert into table values('$val')"; if(false===$pdo->exec($sql)){ echo '执行失败'; }
PDO实现预编译
指的是预先编译sql的结构的一种执行sql的语法
如果执行多条结构相同的sql，编译的中间结果（语法树）应该也是一致的，因此可以将相同的结构，统一编译，每次使用不同的数据执行即可。
编译统一的结构
$pdoStatement = $pdo->prepare(sql结构)
绑定数据到中间编译结果
$pdoStatement ->bindValue()
执行
$pdoStatement ->execute() //$sql = "insert into table values(null,?)"; $sql = "insert into table values(null,:name)"; $stmt = $pdo->prepare($sql); //多组数据也是一编译一执行 //$stmt->bindValue(1,'bee'); $stmt->bindValue(':name','bee'); $res = $stmt->execute(); var_dump($res);
预编译能更好地防止sql注入，是因为预编译时候不需要用户的数据参与，因此编译时结构固定，所以数据不影响到sql结构。
$pdo->query()与$pdo->execute()如果需要防止sql注入，可以使用$pdo->quote()(其作用是先转义后加引号)
PDOstatement常用方法：
errorInfo()
errorCode()
fetchColumn()
fetch()
fetchAll()
rowCount()
closeCursor()
pdo应用
<?php header('content-type:text/html;charset=utf-8'); class PDODB{ static private $_init; private $_host; private $_port; private $_dbname; private $_username; private $_password; private $_charset; private $_dns; private $_pdo; private function __construct($config){ $this->_initParamas($config); $this->_initDNS(); $this->_initDriverOptions(); $this->_initPDO(); } private function __clone(){} static public function getInstance($config){ if(!static::$_init instanceof static){ static::$_init = new static($config); } return static::$_init; } private function _initParamas($config){ $this->_host = isset($config['host'])?$config['host']:'localhost'; $this->_port = isset($config['port'])?$config['port']:'3306'; $this->_dbname = isset($config['dbname'])?$config['dbname']:''; $this->_username = isset($config['username'])?$config['username']:'root'; $this->_passward = isset($config['passward'])?$config['passward']:''; $this->_charset = isset($config['charset'])?$config['charset']:'utf8'; } private function _initDNS(){ $this->_dns = "mysql:host=$this->_host;port=$this->_port;dbname=$this->_dbname"; } private function _initDriverOptions(){ $this->_driverOptions = array( PDO::MYSQL_ATTR_INIT_COMMAND => "set names $this->_charset" ); } private function _initPDO(){ $this->_pdo = new PDO($this->_dns,$this->_username,$this->_passward,$this->_driverOptions) or die("fail"); } public function query($sql){ if(!$result = $this->_pdo->query($sql)){ $erro = $this->_pdo->errorInfo(); echo '失败的语句'.$sql.'<br>'; echo '错误代码'.$erro[1].'<br>'; echo '错误信息'.$erro[2].'<br>'; die; } return $result; } public function fetchAll($sql){ $res = $this->query($sql); $list = $res->fetchAll(PDO::FETCH_ASSOC); $res->closeCursor(); return $list; } public function fetchRow($sql){ $res = $this->query($sql); $row = $res->fetch(PDO::FETCH_ASSOC); $res->closeCursor(); return $row; } public function fetchOne($sql){ $res = $this->query($sql); $one = $res->fetchColumn(); $res->closeCursor(); return $one; } public function escape_string($data){ return $this->_pdo->quote($data); } } $config = array( "host"=>"localhost", "username"=>"root", "passward"=>"root", "dbname"=>"students" ); $pdo = PDODB::getInstance($config); $sql = "select sdept from student where sage=21"; var_dump($pdo->fetchRow($sql)); ?>
运行效果图如下：
