Useful trick: I often have my MySQL account credentials stored in .my.cnf so the mysql command-line client can use them. I also often have Perl scripts which want to connect to the database, and want them to use that file, not have to put the params into the script or have the script read its own config file with the credentials duplicated there.

The answer:

my $dsn = "DBI:mysql:database_name;mysql_read_default_file=$ENV{HOME}/.my.cnf";
my $dbh = DBI->connect($dsn,undef,undef,{RaiseError => 1}) 
    or die "Failed to connect to DB!";

Easy!