# ...
# --------------------
# create db connection
# --------------------
  $dbase = DBI->connect("DBI:Oracle:$dbsid", $dbuser, $dbpassw, { AutoCommit => 0 });
  if (!(defined($dbase))){
# do error handling
}
#
# ----------
# do the sql
# ----------
# ...
  $dbase->{PrintError} = 0;
  $dbsth = $dbase->prepare( $sql );
  $error = $dbase->errstr;
  if (defined ($error) && $error ne "") {
    # error handling
    # errormsg is stored in $error
    # ...
    $dbase->{set_err}=(0, "");
    $dbase->{PrintError} = 1;
    # exit function or so
    # ...
  } else {
    # no error
    $dbase->{set_err}=(0, "");
    $dbase->{PrintError} = 1;
    # ...
  }
# ...