PHP PDO MySQL重复输出 - PHP PDO MySQL duplicate output

PHP PDO MySQL duplicate output

本文关键字：输出 MySQL PDO PHP | 更新日期: 2023-09-27

我使用PHP PDO连接到MySQL数据库并返回结果集，但我似乎得到了重复的输出，尽管我的数据库中只有2条记录。

MYSQL:

mysql> SELECT * FROM nouns;
+-----+---------------+---------+
| PID | german        | english |
+-----+---------------+---------+
|   1 | die Männer    | men     |
|   2 | die Frauen    | women   |
+-----+---------------+---------+
2 rows in set (0.00 sec)
mysql>

PHP代码段1:

$database = new MySQLConnect();
$database->query("SELECT german, english FROM nouns;");
while ($row = $database->row()->fetch()) {
    foreach ($row as $value) {
    $data .= $value;
}

PHP代码段2:

interface IMySQLSettings
{
    const HOSTNAME = "hostname";
    const DATABASE = "database";
    const USERNAME = "username";
    const PASSWORD = "password";
    function __construct();
    function query($query);
    function row();
}
class MySQLConnect implements IMySQLSettings
{
    private $hostname = IMySQLSettings::HOSTNAME;
    private $database = IMySQLSettings::DATABASE;
    private $username = IMySQLSettings::USERNAME;
    private $password = IMySQLSettings::PASSWORD;
    private $connect;
    private $query;
    function __construct()
    {
        $this->connect = new PDO("mysql:host=$this->hostname;dbname=$this->database", $this->username, $this->password);
        $this->connect->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
    }
    function query($query)
    {
        try {
            $this->query = $this->connect->prepare("$query");
            $this->query->execute();
        } catch (PDOException $e) {
            echo $e->getMessage();
        }
    }
    function row()
    {
        return $this->query;
    }
}

输出：

die Männerdie Männermenmendie Frauendie Frauenwomenwomen

在提取中，您必须提供PDO:：fetch_NUM或PDO：：fetch_ASSOC，因为PDO::fetch_BOTH是默认值。

也许当你构建PDO对象时，添加这行

$pdo->setAttribute(PDO::ATTR_DEFAULT_FETCH_MODE, PDO::FETCH_ASSOC);

更多信息PDO fetch_style

以下是您从php.net手册中获得的内容：

PDO::FETCH_ASSOC
Array
(
    [NAME] => apple
    [COLOUR] => red
)
PDO::FETCH_BOTH
Array
(
    [NAME] => banana
    [0] => banana
    [COLOUR] => yellow
    [1] => yellow
)

一个重构版本，去掉了所有无用的代码，但添加了所需的函数。

class MySQLConnect
{
    private $connect;
    function __construct()
    {
        $dsn = "mysql:host=".IMySQLSettings::HOSTNAME.";dbname=".IMySQLSettings::DATABASE;
        $opt = array(
            PDO::ATTR_ERRMODE            => PDO::ERRMODE_EXCEPTION,
            PDO::ATTR_DEFAULT_FETCH_MODE => PDO::FETCH_ASSOC
         );
        $this->connect = new PDO($dsn, IMySQLSettings::USERNAME,IMySQLSettings::PASSWORD, $opt);
    }
    function query($query, $params = array())
    {
        $stmt = $this->connect->prepare($query);
        return $stmt->execute($params);
    }
}
$db = new MySQLConnect();
$stmt = $db->query("SELECT german, english FROM nouns");
foreach ($stmt as $row) {
    foreach ($row as $value) {
    $data .= $value;
}

尽管我保留了IMySQLSettings，但它作为接口是完全无用的
如果我需要另一个数据库来连接怎么办？重新定义MySQLConnect以实现另一个接口？

它必须只是一个数组，传递到MySQLConnect的构造函数中，而不是一个花哨的集成面。