2. ER example : movie & category
M_id
Title
Cat_id
10001
Forest Gump
C102
10002
Iron man
C103
10003
Ender Game
C101
Cat_id
Type
C101
Sci Fi
C102
Drama
C103
Action

3. If we have a new category, we can insert into category.
M_id
Title
Cat_id
10001
Forest Gump
C102
10002
Iron man
C103
10003
Ender Game
C101
Cat_id
Type
C101
Sci Fi
C102
Drama
C103
Action
C104
Cartoon

4. If we have a new category, we can insert into category.
If we change category type, we can do in category. 1 2
M_id
Title
Cat_id
10001
Forest Gump
C102
10002
Iron man
C103
10003
Ender Game
C101
Cat_id
Type
C101
Sci Fi
C102
Drama
C103
Action & Advenger
C104
Cartoon 2 1

5. Maintaining History of Time-Variant Data
Normally, existing attribute values are replaced with new value without regard to previous value
Time-variant data:
Values change over time
Must keep a history of data changes
Keeping history of time-variant data equivalent to having a multivalued attribute in your entity
Must create new entity in 1:M relationships with original entity
New entity contains new value, date of change

7. Fan Traps
Design trap occurs when relationship is improperly or incompletely identified
Represented in a way not consistent with the real world
Most common design trap is known as fan trap
Fan trap occurs when one entity is in two 1:M relationships to other entities
Produces an association among other entities not expressed in the model

10. Supertype/subtype relationships

12. Disjoint and Overlapping Constraints
Disjoint subtypes
Also called nonoverlapping subtypes
Subtypes that contain unique subset of supertype entity set
Overlapping subtypes
Subtypes that contain nonunique subsets of supertype entity set

13. Overlapping subtypes

14. Completeness Constraint
Partial completeness
Symbolized by a circle over a single line
Some supertype occurrences are not members of any subtype
Total completeness
Symbolized by a circle over a double line
Every supertype occurrence must be member of at least one subtype

17. Transforming the ER diagram into relation Schema diagram
The steps:
Map regular entities
Map weak entities
Map binary relationships
Map unary relationships
Map ternary relationships
Mapping Supertype/subtype relationships

18. Mapping a composite attribute

19. Looks like this using relational schema
Relational schema diagram :
Relational schema :
CUSTOMER( Custome_ID, Customer_Name,
Street, City, State, Zip )

20. The 1:M Relationship Between PAINTER and PAINTING

21. Mapping a 1:M relationship

22. Looks like this using relational schema diagram

23. Mapping a binary 1:1 relationship
Some nurse is not in charge for care center  (0,1)
All care centers must have a nurse to be in charge  (1,1)
So,put FK on (0,1) care center

24. Looks like this using relational schema diagram

25. Mapping an M:M relationship

26. Mapping an M:M relationship

27. Looks like this using relational schema diagram

28. Mapping weak entities

29. Looks like this using relational schema diagram

30. Mapping Supertype/subtype relationships

31. Looks like this using relational schema diagram

32. Try this