You initialize $dbh using the first argument to the function, but you then overwrite that variable with a new connection for every loop iteration.

Do one of these:

1. Pass the handle in, do not disconnect in the subroutine
2. Connect at the top of the subroutine, disconnect at the bottom of the subroutine
3. Connect at the top of the loop, disconnect at the bottom of the loop

I would recommend #1 or #2, as #3 is only appropriate if you are connecting to dynamic sources. Very inefficient otherwise.