Detailed explanation of the basic usage of the connect() function

Interacting with databases in PHP is an important part of building dynamic web pages and applications. connect() is not a standard function built into PHP, but a common custom function name, which developers often use to encapsulate database connection logic. By creating our own connect() function, we can improve the reusability and maintainability of our code.

Why use the custom connect() function?

Although PHP provides methods such as mysqli_connect() or PDO for database connections, repeated writing of connection logic can bloat the code. By encapsulation, you can:

• Unified database connection method

• Simplify the code in the main logic

• Easier to error handling and debugging

• Implement centralized management of connection configuration

Example: Connect() function implemented using mysqli

Here is an example of a connect() function that uses the mysqli extension:

function connect() {
$host = 'localhost';
$user = 'db_user';
$password = 'db_password';
$database = 'my_database';

 $conn = new mysqli($host, $user, $password, $database);

if ($conn->connect_error) {
    die('Database connection failed: ' . $conn->connect_error);
}

// Set character set
$conn->set_charset('utf8mb4');

return $conn;

}

// Use example
$conn = connect();

$result = $conn->query("SELECT * FROM users");

while ($row = $result->fetch_assoc()) {
echo "Username: " . $row['username'] . "<br>";
}

$conn->close();
?>

 </code>

## Example：use PDO Implemented connect() function

compared to `mysqli`，PDO Supports multiple database systems and is more secure。以下是use PDO Version：

<code>
```php
<?php

function connect() {
    $dsn = 'mysql:host=localhost;dbname=my_database;charset=utf8mb4';
    $username = 'db_user';
    $password = 'db_password';

    try {
        $pdo = new PDO($dsn, $username, $password, [
            PDO::ATTR_ERRMODE => PDO::ERRMODE_EXCEPTION,
            PDO::ATTR_DEFAULT_FETCH_MODE => PDO::FETCH_ASSOC,
        ]);
        return $pdo;
    } catch (PDOException $e) {
        die('Database connection failed: ' . $e->getMessage());
    }
}

// useExample
$pdo = connect();

$stmt = $pdo->query("SELECT * FROM users");

foreach ($stmt as $row) {
    echo "username: " . $row['username'] . "<br>";
}
?>

Advanced optimization suggestions for connect() function

• Use configuration files : Extract database configuration into .ini or .env files, which is more conducive to management and environment switching.

• Add logging : Write logs when connection fails, not just die() .

• Use singleton mode : Prevent repeated connections to databases in large applications.

Tips: Common errors and solutions for database connections

Conclusion

Although connect() is not a standard function in PHP, it is a common encapsulation method that facilitates developers to manage database connections in a unified manner. Whether you are using mysqli or PDO, implementing a stable and reusable connect() function is the basis for high-quality PHP applications.