We cannot obtain key attributes for a weak entity set indiscriminately. Rather,

Question

We cannot obtain key attributes for a weak entity set indiscriminately. Rather, if E is a weak entity set then its key consists of: 1. Zero or more of its own attributes, and 2. Key attributes from entity sets that are reached by certain many-one relationships from E to other entity sets. These many-one relationships are called supportzng relation.ships for E. In order for R, a many-one relationship from E to some entity set F, to be a I supporting relationship for E, the following conditions must be obeyed: 1) R must be a binary, many-one relationship6 from E to F.? 1.1Rmust have referential integrity from E to F. That is, for every E-entity, the F-entity related to it by R must actually exist in the database. Put another way, a rounded arrow from R to F must be justified.

Explanation / Answer

2. Key attributes from entity sets that are reached by certain many-one relationships from E to other entity sets. 1Rmust have referential integrity from E to F. That is, for every E-entity, the F-entity related to it by R must actually exist in the database

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