How can PHP beginners properly process and handle the results of mysql_query() and mysql_fetch_array() functions?

When using the mysql_query() and mysql_fetch_array() functions in PHP, beginners should properly handle the results to avoid errors or unexpected behavior. To do this, they should check if the query was successful before fetching the results, and handle any errors that may occur during the query execution. Additionally, they should properly loop through the fetched results to access the data.

// Perform a query
$query = mysql_query("SELECT * FROM users");

// Check if the query was successful
if($query){
    // Fetch and loop through the results
    while($row = mysql_fetch_array($query)){
        // Access data from the fetched row
        echo $row['username'] . "<br>";
    }
} else {
    // Handle query errors
    echo "Error executing query: " . mysql_error();
}