Wordpress - Debugging

// Print last SQL query string
$wpdb->last_query
// Print last SQL query result
$wpdb->last_result
// Print last SQL query Error
$wpdb->last_error

http://wordpress.stackexchange.com/questions/34482/preferred-method-of-debugging-a-wordpress-sql-calls

http://wordpress.stackexchange.com/questions/1567/best-collection-of-code-for-your-functions-php-file/4612#4612