..

my $dbh = DBI->connect("dbi:Pg:dbname=Raum;host=127.0.0.1;Port=5342", "perl_db", "****", { RaiseError => 0, AutoCommit => 0 }) or croak $DBI::errstr;     
..

1. Die SQL-Anweisung vorbereiten.
2. Die SQL-Anweisung ausfuehren.
3. Die Ergebnisse abrufen.
4. Die SQL-Transaktion beenden.

# 1. prepare statement handle $sth
$cmd = 'SELECT * FROM table WHERE id = ? AND date > ?'; my $sth = $dbh->prepare_cached($cmd)
    or croak "SQL prepare failed '$cmd': " . $dbh->errstr;

# 2. execute statement (via its handle)
my $rc = $sth->execute(parameter1, parameter2, ...);
   # execute() has as many arguments as the prepared statement ?'s has unless(defined $rc) {
     croak "SQL command failed: " . $dbh->errstr; } else {
     # $rc rows had been effected, e.g. by UPDATE commands }

# 3. fetch results [if any] (again via its handle) while(my $result = $sth->fetchrow_arrayref) {
     # ARRAY ref $result has one entry per column
     # $result->[0] - first column, etc.
}
croak "Failed to get results from SQL command: "
  . $dbh->errstr if $sth->err;
- -or-
while(my $result = $sth->fetchrow_hashref) {
     # HASH ref $result has coumn_name => value pairs
     # $result->{name1}, $name->{name2}, ...
}
croak "Failed to get results from SQL command: "
  . $dbh->errstr if $sth->err;

# 4. finish DB transaction (via DB handle)
$dbh->commit() or die "Failed to save modified data: " . $dbh->errstr;
- -or-
$dbh->rollback() or die "Failed to discard modified data: " . $dbh->errstr;