| A | B |
|---|
| existence dependence | exist in database only when it is associated with another related entity occurrence |
| existence independence | entity can exist apart from one or more related entities. |
| Weak entities are | existence dependent – strong identifiable |
| Optional participation | one entity occurrence doesn’t require a corresponding entity occurrence in a particular relationship |
| Mandatory participation | means that one entity occurrence requires a corresponding entity occurrence in a particular relationship. |
| Relationship degree | indicates number of entities associated with a relationship |
| Unary relationship | association is maintained within single entry |
| Binary relationship | are the most common= when 2 entities are associated. |
| Ternary | an association among 3 different |
| Recursive relationship | relationship can exist between occurrence of the same entity set |
| Composite entities | composed of primary keys of each of the entities to be connected |
