pdo 连接操作数据库

<?php	
/*
 * 开启pdo，php.ini扩展打开即可
预处理:
	1,?    绑定 $stmt->bindparam('1',$name,PDO::PARAM_STR);  //从1始
	2,:name   $stmt->bindparam(':name',$name);  第三个参数可写可不写
	3,execute(数组);
	如何获得受影响行,插入ID rowCount()   lastInsertId()

结果集遍历：4种 
	1,query来foreach   $result = $pdo->query()  可直接foreach $result
	2,bindColumn 绑定列  while($stmt->fetch())
	3,fetch		while($row=$stmt->fetch(PDO::FETCH_ASSOC))
	4,fetchAll	$stmt->fetchall()  返回的是个数组
	如何获取字段[了解]
 */

try{
	$dsn = 'mysql:host=localhost;dbname=test';   //手册查询
	$pdo = new Pdo($dsn,'root','abc123');  //第四个参数 可初始化设置
	$pdo->query('set names utf8');  //字符集
	$pdo->setAttribute(PDO::ATTR_ERRMODE,PDO::ERRMODE_EXCEPTION);

	//字段  select id,username,password from user
	$stmt = $pdo->prepare('desc user');
	$stmt->execute();
	$j = $stmt->columnCount();  //统计列数
	
	for($i=0;$i<$j;$i++){
		echo '<pre>';
		var_dump($stmt->getColumnMeta($i));
		echo '</pre>';
	}
	$stmt->setFetchMode(PDO::FETCH_NUM);
	 
	//PDO::FETCH_NUM
	//PDO::FETCH_ASSOC
	
/*	可直接遍历
	$result = $pdo->query('select username,password from user');
	foreach($result as $key=>$value){
		echo $value['username'].$value['password'].'<br>';
	}
 */
/*	execute(数组);  fetchAll  遍历
	$stmt = $pdo->prepare('select username,password from user where id>:id and username=:username');
	$stmt->execute(array(':id'=>120,':username'=>'养生'));  //带不带冒号均可
	$result = $stmt->fetchAll();
	foreach($result as $value){
		echo $value['password'].'<br>';
	}
 */
/*	//:id  fetch遍历
	$stmt = $pdo->prepare('select username,password from user where id>:id');
	$stmt->bindparam(':id',$id,PDO::PARAM_INT);
	$id = 122;
	$result = $stmt->execute();
	while($row = $stmt->fetch()){
		echo $row['username'].$row['password'];
		echo '<br>';
	}
 */
/*	//绑定列 bindcolumn
	$stmt = $pdo->prepare('select username,password from user where id>?');

//	$stmt->bindparam('1',$p1,PDO::PARAM_STR);
//	$stmt->bindparam('2',$p2,PDO::PARAM_STR);
	$stmt->bindparam('1',$p3,PDO::PARAM_INT);

//	$p1 = 'username';
//	$p2 = 'password';
	$p3 = 120;

	$stmt->execute();

	$stmt->bindcolumn('username',$username);
	$stmt->bindcolumn('password',$password);

	while($stmt->fetch()){
		echo $username;
		echo $password;
		echo '<br>';
	}
 */

}catch(PDOException $e){
	echo $e->getMessage();
}
?>