我尝试使用pdo连接mysql数据库，但它不工作，并给出错误:
Undefined variable: pdo
，我已经写了数据库查询。
连接mysql数据库代码:
<?php
class Mysql
{
public function __construct() {
try
{
$pdo = new PDO ("mysql:host=localhost;dbname=db_project","root", "");
$pdo->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
}
catch (PDOException $e)
{
echo 'connection failed: '.$e->getMessage();
}
}
?>
and the code where I have written the query is
<?php
include("mysql.php");
class database extends Mysql
{
public function selectcheckusername($username)
{
$stmt = $pdo->prepare("SELECT * FROM `tbl_signup` WHERE username = '$username'");
$stmt->bindParam(":username",$username, POD::PARAM_STR);
$stmt->execute();
}
public function insertTablelogin( $username, $password, $email, $address )
{
$stmt = $pdo->prepare("INSERT INTO `tbl_login`(`username`,`password`,`email`,`address`)
VALUES('$username','$password','$email','$address')");
$stmt->bindParam(":username",$username,":password",$password,":email",$email,":address",$address, POD::PARAM_STR);
$query=$stmt->execute();
}
public function selectforgdv()
{
$stmt = $pdo->prepare( "SELECT * FROM `tbl_login`");
$stmt->bindParam(":userId",$userId,":username",$username,":password",$password,":email",$email,":address",$address ,PDO::PARAM_STR);
$stmt->execute();
echo "<pre>";
print_r($stmt->fetchAll());
echo "</pre>";
}
public function selectforuser( $userId )
{
$stmt = $pdo->prepare("SELECT * FROM `tbl_login` WHERE userId = '$userId'");
$stmt->bindParam(':userId',$userId,PDO::PARAM_INT);
$stmt->execute();
echo "<pre>";
print_r($stmt->fetchAll());
echo "</pre>";
}
public function updatetablelogin($userId,$username_save,$password_save,$email_save,$address_save) {
$stmt = $pdo->prepare("UPDATE `tbl_login` SET username ='$username_save', password ='$password_save',
email ='$email_save',address ='$address_save' WHERE userId = '$userId'");
$smmt->execute();
echo $stmt->rowCount();
}
public function deletetablelogin($userId) {
$stmt = $pdo->prepare("DELETE FROM `tbl_login` WHERE userId = '$userId'");
$stmt->bindParam(':userId',$userId,PDO::PARAM_INT);
$stmt->execute();
echo $stmt->rowCount();
}
}
?>
这是一个作用域问题。$pdo只存在于您的__construct方法中。
要使它在其他地方可用，你需要使它成为你的类的一个属性:
<?php
class Mysql
{
var $pdo;
public function __construct() {
try
{
$this->pdo = new PDO ("mysql:host=localhost;dbname=db_project","root", "");
$this->pdo->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
}
catch (PDOException $e)
{
echo 'connection failed: '.$e->getMessage();
}
}
?>
同样，在您的database类中使用$this->pdo而不是$pdo。