Writing SQL should not be done by developers
Writing portable SQL is not easy and developer often makes mistake that are only visible on specific database.
So with python-sql, we already remove almost all the SQL writing but there were still the _sql_constraints. As they are part of the DDL and not the DML, they are not managed by python-sql.
So here is a review15491002 which implement the two types of constraints (Check and Unique) following the same syntax as python-sql.