What are common mistakes made when querying a MySQL database using PHP?

One common mistake when querying a MySQL database using PHP is not properly sanitizing user input, which can lead to SQL injection attacks. To prevent this, always use prepared statements with parameterized queries to securely interact with the database. 

// Connect to the 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);
}

// Prepare a statement
$stmt = $conn->prepare("SELECT * FROM users WHERE username = ?");
$stmt->bind_param("s", $username);

// Set parameters and execute
$username = $_POST['username'];
$stmt->execute();

// Get the result
$result = $stmt->get_result();

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

// Close statement and connection
$stmt->close();
$conn->close();

Keywords

MySQL PHP query errors optimization

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