问题描述
我收到此错误:
致命错误:在布尔值上调用成员函数 fetch()C:xampphtdocs epogeneratormodeldatabase.php 第 34 行
Fatal error: Call to a member function fetch() on boolean in C:xampphtdocs epogeneratormodeldatabase.php on line 34
当我运行此代码时:
class database
{
private $user = 'root';
private $pass = '';
public $pdo;
public function connect() {
try {
$this->pdo = new PDO('mysql:host=localhost; dbname=generatordatabase', $this->user, $this->pass);
echo 'Poczenie nawizane!';
}
catch(PDOException $e) {
echo 'Poczenie nie mogo zosta utworzone: ' . $e->getMessage();
}
}
public function createTable() {
$q = $this->pdo -> query('SELECT * FROM article');
while($row = $q->fetch()) {
echo $row['id'].' ';
}
$q->closeCursor();
}
}
?>
推荐答案
根据 PHP 手册 PDO::查询
PDO::query() 返回一个 PDOStatement 对象，或者失败时返回 FALSE.
PDO::query() returns a PDOStatement object, or FALSE on failure.
看起来您的查询失败(在第 33 行)并因此返回 BOOLEAN (false)，可能是因为在执行时，PDO 尚未连接到包含名为 article.在 connect() 方法中，我看到它尝试连接到名为generatordatabase"的数据库；确保在调用 createTable() 之前建立此连接，否则确保它包含一个名为article"的表.
It looks like your query is failing (on line 33) and thus returning a BOOLEAN (false), likely because at that point in execution, PDO has not connected to a database that contains a table called article. In the connect() method I see that it tries to connect to a db called 'generatordatabase'; ensure this connection is being made prior to calling createTable(), otherwise ensure that it contains a table called 'article'.
我建议添加更多代码示例，例如在触发错误之前调用此类/方法的代码.
I would recommend adding some more code examples, for instance the code that calls this class/method before the error is triggered.
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