[英]using PDO object for a Select query
我是PDO的初学者。 我正在按照教程学习PDO。 我想使用一个简单的select语句来获取用户ID。
但是当我运行index.php
它不显示任何echo
! 我哪里错了?
我有四个文件:
config =>设置用户名和密码...
DB_Connect:
class DB_Connect {
// constructor
function __construct() {
}
// destructor
function __destruct() {
// $this->close();
}
// Connecting to database
public function connect() {
require_once 'include/config.php';
try {
$hostname = DB_HOST ;
$dbname = DB_DATABASE;
$dbh = new PDO("mysql:host=$hostname;dbname=$dbname", DB_USER, DB_PASSWORD);
}
catch(PDOException $e)
{
echo $e->getMessage();
}
return $dbh;
}
}
DB_Functions:
class DB_Functions {
private $db;
//put your code here
// constructor
function __construct() {
require_once 'DB_Connect.php';
// connecting to database
$this->db = new DB_Connect();
$this->db->connect();
}
// destructor
function __destruct() {
}
function getUsers(){
$sql = "SELECT * FROM users";
foreach ($this->$db->query($sql) as $row)
{
echo $row->id;
}
/*** close the database connection ***/
// $db = null;
}
}
的index.php
<?php
require_once 'include/DB_Functions.php';
$qr = new DB_Functions();
$qr->getUsers();
?>
db_connect
class DB_Connect {
public $dbh;
// constructor
function __construct() {
}
// destructor
function __destruct() {
// $this->close();
}
// Connecting to database
public function connect() {
require_once 'include/config.php';
try {
$hostname = DB_HOST ;
$dbname = DB_DATABASE;
$this->dbh = new PDO("mysql:host=$hostname;dbname=$dbname", DB_USER, DB_PASSWORD);
}
catch(PDOException $e)
{
echo $e->getMessage();
}
}
}
db_functions
class DB_Functions {
private $db;
//put your code here
// constructor
function __construct() {
require_once 'DB_Connect.php';
// connecting to database
$this->db = new DB_Connect();
$this->db->connect();
}
// destructor
function __destruct() {
}
function getUsers(){
$sql = "SELECT * FROM users";
foreach ($this->db->dbh->query($sql) as $row)
{
echo $row->id;
}
/*** close the database connection ***/
// $db = null;
}
}
您没有数据库连接,因为您现在正在将PDO连接分配给变量。 因此,其余脚本无法访问您的连接。 至少,这就是我目前的想法。
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