MySql - Aggregate function for choosing first choice, second choice, third choice, etc?

Programmer Question

Imagine I have the following data in a table called "messages":

message_id | language_id | message
------------------------------------
1            en            Hello
1            de            Hallo
1            es            Hola
2            en            Goodbye
2            es            Adios

(Note that I don't have a German translation for "Goodbye.")

I want to select the messages for a user who speaks English and German, but prefers German.

Meaning, I want a result set that looks like:

message_id | language_id | message
------------------------------------
1            de            Hallo
2            en            Goodbye

But, um, it's proving tricky. Any ideas?

Find the answer here