What precautions should be taken when constructing URLs with query strings in PHP to ensure data security and integrity?

When constructing URLs with query strings in PHP, it is important to sanitize and validate user input to prevent SQL injection attacks and other security vulnerabilities. One way to ensure data security and integrity is to use PHP's built-in functions like `filter_var` or `htmlspecialchars` to sanitize input data before appending it to the URL query string. 

// Sanitize and validate user input before constructing the URL
$userInput = filter_var($_GET['user_input'], FILTER_SANITIZE_STRING);

// Construct the URL with sanitized input
$url = 'http://example.com/page.php?user_input=' . urlencode($userInput);

Keywords

SQL injection htmlspecialchars urlencode validation prepared statements

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