What are the differences between PHP and JavaScript in terms of form validation and database querying?

PHP is a server-side language commonly used for form validation and database querying, while JavaScript is a client-side language that can also be used for form validation. PHP form validation typically involves checking form data on the server before processing it, while JavaScript form validation can be done on the client side before submitting the form. When it comes to database querying, PHP is often used to connect to a database and execute queries, while JavaScript is not typically used for this purpose. PHP code snippet for form validation: 

<?php
if ($_SERVER["REQUEST_METHOD"] == "POST") {
    $name = $_POST["name"];
    $email = $_POST["email"];

    // Validate name
    if (empty($name)) {
        $errors[] = "Name is required";
    }

    // Validate email
    if (empty($email)) {
        $errors[] = "Email is required";
    } elseif (!filter_var($email, FILTER_VALIDATE_EMAIL)) {
        $errors[] = "Invalid email format";
    }

    // If no errors, process the form data
    if (empty($errors)) {
        // Process form data
    } else {
        // Display errors
        foreach ($errors as $error) {
            echo $error . "<br>";
        }
    }
}
?>
```

PHP code snippet for database querying:

```php
<?php
// Connect to database
$servername = "localhost";
$username = "username";
$password = "password";
$dbname = "database";

$conn = new mysqli($servername, $username, $password, $dbname);

// Check connection
if ($conn->connect_error) {
    die("Connection failed: " . $conn->connect_error);
}

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

if ($result->num_rows > 0) {
    // Output data of each row
    while($row = $result->fetch_assoc()) {
        echo "Name: " . $row["name"]. " - Email: " . $row["email"]. "<br>";
    }
} else {
    echo "0 results";
}

$conn->close();
?>

Keywords

PHP JavaScript form validation database querying differences

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