I am making a PHP/MySQL message board but I need a little help.
I want to be able to display the author of a post.
I have one table for topics and another for members.
The problem is that in the topics table the author's ID is stored and not the members username. This ID corresponds with the ID in the members table.

I know I can use an SQL statement like:
SELECT UserName from members WHERE members.UserName = topics.Author

But the thing is that I am already executing other SQL statements to get other details of the topic

So I gues what I a m asking is how do I use the above SQL satement within another SQL statement?