Grant Fritchey does some data modeling:
PostgreSQL supports constraints much like any other database management system. When you need to ensure certain behaviors of the data, you can put these constraints to work. I’ve already used several of these in creating my sample database (available articles publicly on GitHub, in the
CreateDatabase.sqlfile). I’ll explain those as we go. The constraints supported by PostgreSQL are:
Read on for the list, which includes one constraint which doesn’t have a direct analog in SQL Server.