Ms SQL has extended properties, particularly the ms_description one that is exposed in ssms. But that's comments on database columns and objects, not data poin

Ms SQL has extended properties, particularly the ms_description one that is exposed in ssms. But that's comments on database columns and objects, not data points. Which highlights the difference between the registry and an rdbms. In an rdbms you can absolutely comment the columns and tables, just not the rows and individual data points. In the registry, the data isn't tabular. Every data point has a corresponding field name. That name absolutely would support a comment in sql.