```ruby
require 'dm-constraints/adapters/dm-do-adapter'

module DataMapper
  module Constraints
    module Adapters

      module OracleAdapter
        include DataObjectsAdapter

        # oracle does not provide the information_schema table
        # To question intenal state like postgres or mysql
        # @see DataMapper::Constraints::Adapters::DataObjectsAdapter
        # @api private
        def constraint_exists?(storage_name, constraint_name)
          statement = <<-SQL.compress_lines
            SELECT COUNT(*)
            FROM USER_CONSTRAINTS
            WHERE table_name = ?
            AND constraint_name = ?
          SQL

          select(statement, storage_name, constraint_name).first > 0
        end


        # @see DataMapper::Constraints::Adapters::DataObjectsAdapter#create_constraints_statement
        def create_constraints_statement(storage_name, constraint_name, constraint_type, foreign_keys, reference_storage_name, reference_keys)
          <<-SQL.compress_lines
            ALTER TABLE #{quote_name(storage_name)}
            ADD CONSTRAINT #{quote_name(constraint_name)}
            FOREIGN KEY (#{foreign_keys.join(', ')})
            REFERENCES #{quote_name(reference_storage_name)} (#{reference_keys.join(', ')})
            INITIALLY DEFERRED DEFERRABLE
          SQL
        end

        def destroy_constraints_statement(storage_name, constraint_name)
          <<-SQL.compress_lines
            ALTER TABLE #{quote_name(storage_name)}
            DROP CONSTRAINT #{quote_name(constraint_name)}
            CASCADE
          SQL
        end

        def drop_table_statement(model)
          table_name = quote_name(model.storage_name(name))
          "DROP TABLE #{table_name} CASCADE_CONSTRAINTS"
        end
      end
    end
  end
end
```

Remove the drop_table from the oracle adapter.
user
```ruby
require 'dm-constraints/adapters/dm-do-adapter'

module DataMapper
  module Constraints
    module Adapters

      module OracleAdapter
        include DataObjectsAdapter

        # oracle does not provide the information_schema table
        # To question intenal state like postgres or mysql
        # @see DataMapper::Constraints::Adapters::DataObjectsAdapter
        # @api private
        def constraint_exists?(storage_name, constraint_name)
          statement = <<-SQL.compress_lines
            SELECT COUNT(*)
            FROM USER_CONSTRAINTS
            WHERE table_name = ?
            AND constraint_name = ?
          SQL

          select(statement, storage_name, constraint_name).first > 0
        end


        # @see DataMapper::Constraints::Adapters::DataObjectsAdapter#create_constraints_statement
        def create_constraints_statement(storage_name, constraint_name, constraint_type, foreign_keys, reference_storage_name, reference_keys)
          <<-SQL.compress_lines
            ALTER TABLE #{quote_name(storage_name)}
            ADD CONSTRAINT #{quote_name(constraint_name)}
            FOREIGN KEY (#{foreign_keys.join(', ')})
            REFERENCES #{quote_name(reference_storage_name)} (#{reference_keys.join(', ')})
            INITIALLY DEFERRED DEFERRABLE
          SQL
        end

        def destroy_constraints_statement(storage_name, constraint_name)
          <<-SQL.compress_lines
            ALTER TABLE #{quote_name(storage_name)}
            DROP CONSTRAINT #{quote_name(constraint_name)}
            CASCADE
          SQL
        end

      end
    end
  end
end
```
assistant