Super type or Sub type - Normalization of Database Tables

What kind of constraint specifies whether each entity super type occurrence must also be a member of at least one sub-type?

Completeness Constraints specifies whether each entity super-type occurrence must also be a member of at least one sub-type. This Constraint of completeness can be total or partial.  Which means partial completeness that every super type occurrence is a member of a sub-type; that is, there may be some super-type occurrences that are not members of any sub-type. And the meaning of Total completeness "every super-type occurrence must be a member of at least one sub-type".

Database normalization (or normalisation) organizing process of columns and rows and tables to minimize the data redundancy of relational database.

So creating redundant data is not to lose the data. It't just to normalize them. The main purpose of defining foreign keys in old tables refrerencing the primary key of the new ones. So we isolate data in additions we can do deletion and updation  of any row or column with in one table. And then propagate the rest database using defined foreign key.