Return a string instead of field value when condition is met in MySQL

With my ongoing saga to try to do things directly in the database instead of using some php-logic, another question. For instance: I've got a table: `m/ id | by | msg` an id, by who is this done and what is the message. The `by` field is an integer connected to another table which stores the name. Normally I would left join the two tables: ``` SELECT m.id, m.msg, user.name FROM m LEFT JOIN user ON m.by = u.id ``` With the resulting relation, e.g.: ``` 1 | Hello World | Richard 2 | Foo Bar | Some else 3 | Howdy | Richard ``` I'm richard and have `user.id=4` Is it possible to have the resulting relation to display `you` instead of `Richard` where the condition `user.id = (int)` is met?