How can PHP developers ensure the compatibility and stability of their code when incorporating new mysqli_ functions alongside existing mysql_ functions in a project?

To ensure compatibility and stability when incorporating new mysqli_ functions alongside existing mysql_ functions, PHP developers should gradually migrate their codebase to use mysqli_ functions exclusively. This can be done by updating the existing mysql_ functions to their mysqli_ equivalents and testing the code thoroughly to ensure it works as expected. Additionally, developers should consider using error handling mechanisms to catch any potential issues during the migration process.

// Example code snippet for migrating from mysql_ to mysqli_ functions
// Connect to MySQL using mysqli
$mysqli = new mysqli("localhost", "username", "password", "database");

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

// Perform a query using mysqli
$result = $mysqli->query("SELECT * FROM table");

// Fetch data from the result set
while ($row = $result->fetch_assoc()) {
    echo "Column1: " . $row["column1"] . " - Column2: " . $row["column2"];
}

// Close the connection
$mysqli->close();