Guidelines for Naming Columns
As it has been defined so far, this column naming convention fails to define the Date domain with enough rigor to prevent an application developer from comparing a shipping date with a birth or hire date, but it provides a sufficient example for illustration as well as a first approximation to how you might define a domain rigorously.
Because ANSI/ISO SQL does not have facilities for defining domains with this level of rigor, your only course of action is to do so textually or to create appropriate distinct user‑defined data types (see SQL Data Definition Language and SQL External Routine Programming for details about how to create UDTs and their associated database objects). Be aware that you cannot specify constraints on UDT columns, so their usefulness for defining domains is less than it might otherwise be.
You can record these distinctions in several ways.
Create this comment string using the COMMENT SQL statement.
View the comment you create using the Columns system view.
After you have rigorously defined your domains textually, your next step should be to name your columns by qualifying those domain names.