# File lib/dm-core/migrations.rb, line 846
      def sequence_exists?(sequence_name)
        return false unless sequence_name
        statement = "SELECT COUNT(*)\nFROM all_sequences\nWHERE sequence_owner = ?\nAND sequence_name = ?\n".compress_lines

        query(statement, schema_name, oracle_upcase(sequence_name)).first > 0
      end