Obtain DBMS specific SQL code portion needed to set the FOREIGN KEY constraint
        of a field declaration to be used in statements like CREATE TABLE.

        :param foreign_key: The foreign key
        :type foreign_key: ForeignKeyConstraint

        :rtype: str

def get_foreign_key_declaration_sql(self, foreign_key):
        """
        Obtain DBMS specific SQL code portion needed to set the FOREIGN KEY constraint
        of a field declaration to be used in statements like CREATE TABLE.

        :param foreign_key: The foreign key
        :type foreign_key: ForeignKeyConstraint

        :rtype: str
        """
        sql = self.get_foreign_key_base_declaration_sql(foreign_key)
        sql += self.get_advanced_foreign_key_options_sql(foreign_key)

        return sql