<?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 $result2,bindColumn 绑定列  while($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();
}
?>