my $dbh = DBI->connect( "dbi:Oracle:$db_host", $db_user, $db_pass,
                      ) || die "Database connection not made: $DBI::errstr";
...
my $sth = $dbh->prepare(q{
      INSERT into DGKTO_BASIS
      ( Feld1, Feld2, Feld3, Feld4 )
      ) values (
        ?, ?, TO_DATE(?,'YYYYMMDD'), ?
    }) || die "Can't prepare statement: $DBI::errstr";
...
# Hauptschleife
...
    eval {
        $sth->execute ($feld1, $feld2, $feld3, $feld4);
    };

    if ( $DBI::err ) {
         # weiterer Code 
    }