1) go to Adminer demo http://adminer.sourceforge.net/adminer.php?username=
2) in 'SQL command' paste the query:
CREATE VIEW `duration_with_ifnull` AS SELECT duration as duration, IFNULL(`duration`,'') AS `IFNULL(duration)` FROM `songs`;
3) Go to database and select view 'duration_with_ifnull'
4) Notice how values in columns 'duration' and 'IFNULL(duration)' are different
'3' is added before every number and ':' is replaced by 'a'