What are the potential pitfalls of using global variables in PHP functions and how can they impact database operations?

Using global variables in PHP functions can lead to code that is difficult to maintain and debug, as it introduces dependencies that are not explicit. This can make it harder to track down bugs and understand the flow of the program. Additionally, global variables can impact database operations by making it harder to ensure data integrity and security, as the state of the global variables can change unpredictably. To avoid using global variables in PHP functions, you can pass the necessary variables as parameters to the function. This makes the dependencies explicit and helps to isolate the function's behavior.

// Avoid using global variables by passing necessary variables as parameters
function fetchDataFromDatabase($connection, $tableName) {
    $query = "SELECT * FROM $tableName";
    $result = mysqli_query($connection, $query);
    
    // Process the result...
}

// Example of calling the function with necessary variables
$connection = mysqli_connect("localhost", "username", "password", "database");
$tableName = "users";
fetchDataFromDatabase($connection, $tableName);