For every relationship, there are six possible referential integrity actions.

More Questions from Data Models into Database Designs

• In 1:N relationships, which entity becomes the parent entity is arbitrary.
• A foreign key is used to implement relationships between tables.
• All primary keys are required.
• When the parent entity is required, a new parent row can always be inserted.
• When the parent entity is required, cascading updates and cascading deletions should be allowed or the associated actions on the parent should be prohibited.
• An intersection table is required to represent M:N relationships.
• In a 1:1 relationship, the primary key placement is arbitrary.
• For every relationship, there are six possible sets of minimum cardinalities.
• Cascading updates refers to child rows being automatically deleted when a parent row is deleted.
• Surrogate keys have much meaning for users.

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