Do I really need to use the Perl foreach command to do this?

What do you mean by need? The commands seem like perfectly valid SQL commands to me, so the obvious answer seems no to me. Clearly, if the SQL works, you don't need any other solution.

Perhaps you mean, what is the most efficient solution? In general, it's more efficient to do more work on the database server than outside the server, but sometimes, it doesn't. This can be due to the wanted result, or it can be because of a slow database server, and a fast machine to do calculations on.

Since your local conditions are impossible to know for us, there's just one way to solving this question: benchmark.

Abigail