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pages/总复习2023t1.md

@@ -973,6 +973,7 @@
 						  id:: 64896085-645b-408f-b17a-109b6cd82aeb
 						  specialization/generalization:
 							- participation constraints :-> Determines whether every member in superclass
+							  id:: 6489683b-319a-4173-a55b-6fa3b2c09aeb
 							  must participate as a member of a subclass.
 								- May be mandatory or optional. #flashcard
 								  id:: 648960d0-ae7f-4452-a1b9-cab8a9b13443
@@ -980,10 +981,8 @@
 									  member of subclass
 									- Optional: member of superclass may be member
 									  of subclass.
-							- disjoint constraints :-> Describes relationship between members of the
-							  subclasses and indicates whether member of a
-							  superclass can be a member of one, or more than
-							  one, subclass. #flashcard
+							- disjoint constraints :-> Describes relationship between members of the subclasses and indicates whether member of a superclass can be a member of one, or more than one, subclass. #flashcard
+							  id:: 6489683b-039f-4161-94b1-91177f713ee5
 								- Disjoint: member of superclass is member of at
 								  most one subclass
 								- Disjoint: member of superclass is member of at
@@ -1002,12 +1001,10 @@
 						- Subclass :-> A distinct subgrouping of occurrences of an entity
 						  id:: 64895f39-d886-436b-9afe-ba75d37c8b45
 						  type.
-						- When to use them? eith
-						  1. There are attributes that apply to some (but
-						  not all) instances of an entity.
-						  2. The instances of a potential subclass
-						  participate in a relationship unique to that
-						  subclass.
+						- When to use them? either one or both #flashcard
+						  id:: 6489683b-7d47-4246-afdf-83fdb35a00f6
+							- There are attributes that apply to some (but not all) instances of an entity.
+							- The instances of a potential subclass participate in a relationship unique to that subclass.
 				- LATER designing ER diagram
 			- DONE Block 3
 			  collapsed:: true