\begin{tabular}{l} These entities and attributes become tables and primary keys. \\ Publication \\ PublicationName R U \\ The many-many relationship is implemented as a new table. Select all possible primary keys of \\ the new table for two business rules: \\ A person can have multiple subscriptions to a publication. \\ \( \square \) PersonID \\ PublicationName \\ (PersonID, PublicationName) \\ (PublicationName, PersonID) \\ The composite of PersonID, PublicationName, and a third column of the new table \\ A person can only subscribe to a publication once. \\ \( \square \) PersonID \\ \( \square \) PublicationName \\ \( \square \) (PersonID, PublicationName) \\ \( \square \) (PublicationName, PersonID) \\ The composite of PersonID, PublicationName, and a third column of the new table \\ \hline\end{tabular}

To determine the possible primary keys for the new table that represents the many-to-many relationship between persons and publications, we need to analyze the two business rules provided. ### Business Rule Analysis 1. **A person can have multiple subscriptions to a publication.** - This means that the relationship between a person and a publication is not unique; a person can subscribe to the same publication multiple times. Therefore, we cannot use just `PersonID` or `PublicationName` as primary keys since they would not uniquely identify a record in this case. - The possible primary keys in this scenario would be: - **(PersonID, PublicationName)**: This composite key would uniquely identify each subscription since it combines both the person and the publication. - **(PublicationName, PersonID)**: This is essentially the same as the previous composite key but in a different order. It would also uniquely identify each subscription. 2. **A person can only subscribe to a publication once.** - In this case, the relationship is unique; each person can only have one subscription to each publication. Therefore, both `PersonID` and `PublicationName` can be used as primary keys individually. - The possible primary keys in this scenario would be: - **PersonID**: This would uniquely identify a person. - **PublicationName**: This would uniquely identify a publication. - **(PersonID, PublicationName)**: This composite key would still work since it uniquely identifies the subscription. - **(PublicationName, PersonID)**: This is the same composite key as above but in a different order, which would also work. ### Summary of Possible Primary Keys - For the first business rule (multiple subscriptions): - **(PersonID, PublicationName)** - **(PublicationName, PersonID)** - For the second business rule (only one subscription): - **PersonID** - **PublicationName** - **(PersonID, PublicationName)** - **(PublicationName, PersonID)** ### Conclusion In conclusion, the possible primary keys for the new table based on the two business rules are: - **(PersonID, PublicationName)** - **(PublicationName, PersonID)** - **PersonID** (only for the second rule) - **PublicationName** (only for the second rule) Thus, the correct selections for the primary keys based on the business rules are: - **(PersonID, PublicationName)** - **(PublicationName, PersonID)** (for the first rule) - **PersonID** (for the second rule) - **PublicationName** (for the second rule)