plperl and table/record access

Hi.

How do I manipulate data in tables from within plperl? Can I, for example, 
issue SQL statements from within plperl functions? I haven't managed to find 
any documentation on this subject. Can anyone point me in the correct 
direction, please? I'm trying to write some trigger functions...

I have seen an example with the plperl function that performs a calculation 
on each row of a table, but it is not explained anywhere how to insert 
records, or how to locate specific records without having to loop through the 
entire database. I presume that DBI will not work, given the need for setting 
up separate database connections, authentication, etc.

Thanks.

Gordan