Put the data from a MySQL column in an array

[RPicard]

I'm basically looking to get the data from a specific column, only in rows where a condition is true, and put it into an array.

For example (it's a message system):

To.....Message....Subject
user1..example.....example
user2..example2....example

In this example I would want to put the subjects of the messages to user1 in an array.

Any ideas?