diff --git a/pages/总复习2023t1.md b/pages/总复习2023t1.md index 74b2de9..25738c5 100644 --- a/pages/总复习2023t1.md +++ b/pages/总复习2023t1.md @@ -961,6 +961,20 @@ - LATER EER - Most useful additional concept of EER model: specialization/generalization. + - Specialization + - Process of maximizing differences between + members of an entity by identifying their + distinguishing characteristics. + - Generalization + - Process of minimizing differences between + entities by identifying their common + characteristics. + - Two constraints that may apply to a + specialization/generalization: + - participation constraints + - May be {{c1 mandatory}} or {{c1 optional}}. + - disjoint constraints + - Superclass / Subclass - Superclass :-> An entity type that includes one or more distinct id:: 64895f2f-b868-46ec-9d80-7079eaf3197d subgroupings of its occurrences. @@ -974,19 +988,6 @@ - Subclass :-> A distinct subgrouping of occurrences of an entity id:: 64895f39-d886-436b-9afe-ba75d37c8b45 type. - - Specialization - - Process of maximizing differences between - members of an entity by identifying their - distinguishing characteristics. - - Generalization - - Process of minimizing differences between - entities by identifying their common - characteristics. - - Two constraints that may apply to a - specialization/generalization: - - participation constraints - - disjoint constraints - - - LATER designing ER diagram - DONE Block 3 collapsed:: true