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PHP Database Connection Pitfalls: Avoid Common Mistakes and Misunderstandings
PHP Database Connection Pitfalls: Avoid Common Mistakes and Misunderstandings
Jun 05, 2024 pm 10:21 PM
To avoid PHP database connection errors, follow best practices: check for connection errors and variable names matching credentials. Use secure storage or environment variables to avoid hardcoding credentials. Close the connection after use, prevent SQL injection, use prepared statements or bind parameters.
PHP Database Connection Traps: Avoid Common Mistakes and Misunderstandings
It's easy to fall into common traps and encounter errors when using PHP to connect to a database. To prevent these problems, it is crucial to master correct connection techniques.
PHPMyAdmin connection
Use PHPMyAdmin to connect to the database:
<?php
$servername = "localhost";
$username = "username";
$password = "password";
$dbname = "database_name";
// 創(chuàng)建連接
$conn = new mysqli($servername, $username, $password, $dbname);
// 檢查連接錯誤
if ($conn->connect_error) {
die("連接失敗: " . $conn->connect_error);
}
// 使用數(shù)據(jù)庫
$sql = "SELECT * FROM table_name";
$result = $conn->query($sql);
if ($result->num_rows > 0) {
// 在這里處理結(jié)果
} else {
echo "沒有結(jié)果";
}
// 關(guān)閉連接
$conn->close();
?>PDO connection
Use PDO to connect to the database:
<?php
$dsn = "mysql:host=localhost;dbname=database_name";
$username = "username";
$password = "password";
// 創(chuàng)建連接
try {
$conn = new PDO($dsn, $username, $password);
$conn->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
} catch(PDOException $e) {
die("連接失敗: " . $e->getMessage());
}
// 使用數(shù)據(jù)庫
$stmt = $conn->prepare("SELECT * FROM table_name");
$stmt->execute();
foreach ($stmt->fetchAll() as $row) {
// 在這里處理結(jié)果
}
// 關(guān)閉連接
$conn = null;
?>Avoid common mistakes
- Unchecked connection errors: Always check if the connection was successful and handle errors correctly.
- Inconsistent variable names: Variable names (such as
$username) must match database credentials. - Use hardcoded credentials: It is not safe to store database credentials in PHP files. Secure storage or environment variables should be used.
- Unclosed connection: After use, always close the connection to release resources.
- Use unsafe SQL queries: Use prepared statements or bound parameters to prevent SQL injection.
Practical case
Connecting to a remote MySQL database:
<?php // 遠程數(shù)據(jù)庫服務(wù)器信息 $servername = "remote.example.com"; $username = "remote_username"; $password = "remote_password"; $dbname = "remote_database_name"; // 創(chuàng)建連接 $conn = new mysqli($servername, $username, $password, $dbname); // 使用數(shù)據(jù)庫 echo "連接至遠程數(shù)據(jù)庫成功！"; // 關(guān)閉連接 $conn->close(); ?>
By following these best practices, you can avoid common PHP database connections Errors to ensure your application interacts with the database safely and error-free.
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