my $database = 'TEST_DB';
my $DSN = "dbi:Oracle:$database";
my $dbh = DBI->connect( $DSN,
                          $DBUSER,
                          $DBPASS,
                          {AutoCommit => 1, RaiseError => 1}) or die "Can't connect DB [$!]";


##</code><code>##

.../oracle/product/10.2.0/client_1/network/admin/tnsnames.ora

TEST_DB =
  (DESCRIPTION =
    (ADDRESS = (PROTOCOL = TCP)(Host = 192.168.1.1)(Port = 1526))
    (CONNECT_DATA =
      (SID = TESTDB)
    )
  )



##</code><code>##

DBI connect('TEST_DB','user',...) failed: ORA-01031: insufficient privileges (DBD ERROR: OCISessionBegin)