PDO PHP连接,致命错误 [英] PDO PHP Connection, Fatal Error
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问题描述
我的连接类; firstcode.php
My Connection Class;firstcode.php
class DB_functions {
public $db;
function __construct() {
try{
$db = new PDO("mysql:localhost;dbname=xxx;charset=utf8","xxx","xxx");
echo 'Connected';
}catch(PDOException $e){
print $e->getMessage();
echo "No Connection";
}
}
function __destruct() {}
public function test(){
$query = $db->query("SELECT * FROM User", PDO::FETCH_ASSOC);
if($query->rowCount()){
foreach ($query as $row) {
print_r($row);
}
}
}
}
我的测试PHP文件;
My test PHP File;
<?php
require_once('firstcode.php');
$db = new db_functions();
$t = $db->test();
?>
还有我得到的错误;
注意:未定义的变量:第20行上firstcode.php中的db
Notice: Undefined variable: db in firstcode.php on line 20
致命错误:第20行上firstcode.php中非对象上调用成员函数query()
Fatal error: Call to a member function query() on a non-object in firstcode.php on line 20
预先感谢
推荐答案
您快到了.在您的课程中,您需要使用以下命令更改$db
的每次迭代:
You're almost there. In your class, you need to change each iteration of $db
with:
$this->db
所以您的课程看起来像这样:
So your class would look like this:
class DB_functions {
public $db;
function __construct() {
try{
$this->db = new PDO("mysql:localhost;dbname=xxx;charset=utf8","xxx","xxx");
echo 'Connected';
}catch(PDOException $e){
print $e->getMessage();
echo "No Connection";
}
}
function __destruct() {}
public function test(){
$query = $this->db->query("SELECT * FROM User", PDO::FETCH_ASSOC);
if($query->rowCount()){
foreach ($query as $row) {
print_r($row);
}
}
}
}
在引用内部类变量时.它只能在类范围内访问,并通过$this
引用.
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