# connect to mesh db
my $dbh = DBI->connect( "dbi:Pg:dbname=foobar", "foo") 
|| die "couldn't open db \n";
# prepare statement, $dtable is the table name I am passing in as a parameter
my $rm = $dbh->prepare("DELETE FROM  $dtable (pubmed_ui) VALUES (?)");
# when I parse from xml file
my $pmid = ($root->descendants('PMID'))[0]->text;   
print "PMID: $pmid\n";
$rm->execute($pmid);