test

<?php
$mysqli = new mysqli("localhost", "user", "password", "database");

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

// Prepare a statement
$stmt = $mysqli->prepare("SELECT * FROM users WHERE username = ?");
$stmt->bind_param("s", $username); // "s" denotes the type (string) of the parameter
$username = $_POST['username'];

// Execute the query
$stmt->execute();
$result = $stmt->get_result();
while ($row = $result->fetch_assoc()) {
  echo "User: " . $row['username'];
}

// Close the statement and connection
$stmt->close();
$mysqli->close();
?>

<?php
try {
  $pdo = new PDO("mysql:host=localhost;dbname=database", "user", "password");
  $pdo->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);

  // Prepare a statement
  $stmt = $pdo->prepare("SELECT * FROM users WHERE username = :username");
  $stmt->bindParam(':username', $username);
  $username = $_POST['username'];

  // Execute the query
  $stmt->execute();
  while ($row = $stmt->fetch(PDO::FETCH_ASSOC)) {
    echo "User: " . $row['username'];
  }
} catch (PDOException $e) {
  echo "Error: " . $e->getMessage();
}

// Close the connection
$pdo = null;
?>

<?php
$mysqli = new mysqli("localhost", "user", "password", "database");

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

// Prepare a statement with multiple parameters
$stmt = $mysqli->prepare("SELECT * FROM users WHERE username = ? AND email = ? AND age = ?");
$stmt->bind_param("ssi", $username, $email, $age); // "s" denotes string, "i" denotes integer

// Assigning values to the variables
$username = $_POST['username'];
$email = $_POST['email'];
$age = (int)$_POST['age'];

// Execute the query
$stmt->execute();
$result = $stmt->get_result();

while ($row = $result->fetch_assoc()) {
  echo "User: " . $row['username'] . ", Email: " . $row['email'] . ", Age: " . $row['age'];
}

// Close the statement and connection
$stmt->close();
$mysqli->close();
?>

$stmt->close();
$mysqli->close();