What are the best practices for securely retrieving data from a database in PHP, especially when using user input as part of the query?

When retrieving data from a database in PHP, especially when using user input as part of the query, it is crucial to sanitize and validate the input to prevent SQL injection attacks. One of the best practices is to use prepared statements with parameterized queries to separate the SQL query from the user input, ensuring that the input is treated as data and not executable code. 

// Example of securely retrieving data from a database using prepared statements

// Assuming $conn is the database connection object

// Sanitize and validate user input
$user_input = filter_var($_POST['input'], FILTER_SANITIZE_STRING);

// Prepare the SQL query with a parameter placeholder
$stmt = $conn->prepare("SELECT * FROM table WHERE column = ?");

// Bind the user input to the parameter placeholder
$stmt->bind_param("s", $user_input);

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

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

// Fetch the data
while ($row = $result->fetch_assoc()) {
    // Process the data
}

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

Keywords

SQL injection prepared statements PDO mysqli_real_escape_string parameterized queries

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