When the action Cascade propagates the changes that were made to a primary key
out to the associated foreign key, which of the following are the outcomes? Select all
that apply.
Rows containing invalid foreign keys are deleted when the primary key is
deleted.
Rows containing valid foreign keys are inserted when the primary key is inserted.
Invalid foreign keys are set to the new primary key value when a primary key is
updated.
Rows containing valid foreign keys are deleted when the primary key is deleted.
Rows containing valid foreign keys are inserted when the primary key is
duplicated.

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UpStudy AI · Accepted Answer

To analyze the outcomes of cascading actions in a database when changes are made to a primary key, we need to understand how foreign keys relate to primary keys and the implications of cascading actions. Here are the possible outcomes based on the options provided:

1. **Rows containing invalid foreign keys are deleted when the primary key is deleted.**
   - This is **true**. When a primary key is deleted, any associated foreign keys that reference that primary key become invalid. If cascading delete is enabled, those rows with invalid foreign keys will be deleted.

2. **Rows containing valid foreign keys are inserted when the primary key is inserted.**
   - This is **false**. Inserting a primary key does not automatically insert rows with foreign keys. Foreign key rows must be inserted explicitly.

3. **Invalid foreign keys are set to the new primary key value when a primary key is updated.**
   - This is **false**. Invalid foreign keys cannot be automatically updated to a new primary key value. If a foreign key is invalid, it typically needs to be handled separately (e.g., deleted or updated to a valid value).

4. **Rows containing valid foreign keys are deleted when the primary key is deleted.**
   - This is **true**. If cascading delete is enabled, when a primary key is deleted, all rows that contain valid foreign keys referencing that primary key will also be deleted.

5. **Rows containing valid foreign keys are inserted when the primary key is duplicated.**
   - This is **false**. Duplicating a primary key is generally not allowed in relational databases, as primary keys must be unique. Therefore, no rows with foreign keys would be inserted as a result of duplicating a primary key.

### Summary of Outcomes:
- **True**: 
  - Rows containing invalid foreign keys are deleted when the primary key is deleted.
  - Rows containing valid foreign keys are deleted when the primary key is deleted.
  
- **False**: 
  - Rows containing valid foreign keys are inserted when the primary key is inserted.
  - Invalid foreign keys are set to the new primary key value when a primary key is updated.
  - Rows containing valid foreign keys are inserted when the primary key is duplicated.

Thus, the correct outcomes are the first and fourth options.
When a primary key is deleted, rows with invalid foreign keys are deleted, and rows with valid foreign keys are also deleted.

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