php MySql PDO 连接到数据库
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MySql PDO connection to database
提问by Marc Guerin
I am learning PDO and i am getting very confused, I have this piece of code below and all look right to me however am getting this error code and i dont know what I have to do to fix it, please help me :
我正在学习 PDO 并且我感到非常困惑，我在下面有这段代码，对我来说都是正确的，但是我收到了这个错误代码，我不知道我必须做什么来修复它，请帮助我：
<?php
$hostname='localhost';
$username='root';
$password='';
try {
$dbh = new PDO("mysql:host=$hostname;dbname=stickercollections",$username,$password);
echo 'Connected to Database<br/>';
$sql = "SELECT * FROM stickercollections";
foreach ($dbh->query($sql) as $row)
{
echo $row["collection_brand"] ." - ". $row["collection_year"] ."<br/>";
}
$dbh = null;
}
catch(PDOException $e)
{
echo $e->getMessage();
}
?>
Error Code : Invalid argument supplied for foreach() in /Applications/XAMPP/xamppfiles/htdocs/GOTSWAPMAIN/index.php on line 11
错误代码 ： Invalid argument supplied for foreach() in /Applications/XAMPP/xamppfiles/htdocs/GOTSWAPMAIN/index.php on line 11
回答by Anton Bessonov
Try to increase error mode:
尝试增加错误模式：
<?php
$hostname='localhost';
$username='root';
$password='';
try {
$dbh = new PDO("mysql:host=$hostname;dbname=stickercollections",$username,$password);
$dbh->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION); // <== add this line
echo 'Connected to Database<br/>';
$sql = "SELECT * FROM stickercollections";
foreach ($dbh->query($sql) as $row)
{
echo $row["collection_brand"] ." - ". $row["collection_year"] ."<br/>";
}
$dbh = null;
}
catch(PDOException $e)
{
echo $e->getMessage();
}
?>
EDIT:pdo.error-handlingsays, you can alternatively use pdo.errorcodeand pdostatement.errorcode(or like) to get more info, but I think throw exception is better way to handle bad connections, not resolved hosts etc.
编辑：pdo.error-handling说，你可以选择使用pdo.errorcode和pdostatement.errorcode（或类似的）来获取更多信息，但我认为抛出异常是处理错误连接、未解析主机等的更好方法。
