PHP数据对象PDO操作技巧小结

本文实例讲述了PHP数据对象PDO操作技巧。分享给大家供大家参考，具体如下：PHP数据对象（

本文实例讲述了PHP数据对象PDO操作技巧。分享给大家供大家参考，具体如下：

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：