将pdo :: query设为静态 [英] Make pdo::query static

问题描述

运行下面的代码时出现此错误.我通常使用msql函数，但是我尝试改为使用PDO.怎么了?

I get this error when I run the code below. I have normally used the msql functions butI have tried to get to use the PDO instead. What is wrong ?

致命错误:第14行不能静态调用非静态方法PDO :: query().

Fatal error: Non-static method PDO::query() cannot be called statically on line 14

<?php 

if(isset($_POST['username']) AND isset($_POST['password'])) {

$username = $_POST['username'];
$password = $_POST['password'];
$password_hash = md5($password);

if (!empty($username) AND !empty($password) ) {


$query = "SELECT 'id' FROM `userdatabase` WHERE 'email'='$username' AND      'password'='$password_hash'";

if($query_run = PDO::query($query)){

$query_num_rows = PDO::rowcount($query_run);
if ($query_num_rows==0){
echo 'invalid password/username';

} else {
echo 'Username/password  = correct';
}


}


} else {
echo 'You must enter a password..';
}

} 


?>

推荐答案

::符号用于调用定义为静态的方法，这意味着您无需创建对象实例即可调用此方法. query()方法不是静态的，这意味着您需要先创建PDO对象，然后在该对象上调用query()方法.

:: sign is used to call methods that are defined as static, which means you don't need to create instance of an object to call this method. query() method is not static which means that you need to create PDO object first and then call query() method on that object.

这应该看起来像这样:

$dsn = 'mysql:dbname=testdb;host=127.0.0.1';
$user = 'dbuser';
$password = 'dbpass';
$pdo = new  PDO($dsn, $user, $password);
$result = $pdo->query('SELECT * FROM table');  //here $result is a set of results that can be accessed like arrays;

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