I don't really know what your problem is, or what you are trying to achieve.

So you want:

1. Read a CSV file 'patentes.csv', and for each line take the first and third column, and do something with that data

2. With the ID you extracted in Step 1 you create a filename.

3. now you write something into that file.

Is that correct?

In the last SQL query you have a 'SELECT' but now 'FROM', this looks suspicious to me. Where do you want to take your data from?

In the first query you select '*' but you only use the first column - where's the sense in that?

BTW I recommend to derefernce array refs as $row->[0].

And please use warnings;