A Database Example 

• Raising exceptions - the hard way

my $attr = { AutoCommit => 0 };
my $dsn  = 'dbi:Pg:dbname=products';

sub get_categories_by_mgr {
  my($prod_mgr_id) = @_;

  my $dbh = DBI->connect($dsn, $user, $pswd, $attr)
    or die $DBI::errstr;

  my $sql = 'SELECT * FROM prod_category WHERE prod_mgr_id = ?';
  my $sth = $dbh->prepare($sql) or die $dbh->errstr;
  $sth->execute($prod_mgr_id)   or die $dbh->errstr;

  my @categories;
  while(my $row = $sth->fetchrow_arrayref) {
    push @categories, $row;
  }
  die $sth->errstr if $sth->err;

  $dbh->disconnect or die $dbh->errstr;

  return \@categories;
}