DBMS Chapter 9

Question 1

Step 1: Mapping of Regular Entity Types

Answer 1

For every entity give it a box

Question 2

Step 2: Mapping of Weak Entity Types

Answer 2

give a box for all weak entities but give them a foreign key to the owner entity

Question 3

Step 3: Mapping of Binary 1:1 Relation Types

3 Approaches

Answer 3

Foreign Key approach:
Merged relation option:
Cross-reference option:

Question 4

Step 4: Mapping of Binary 1:N Relationship Types.

Answer 4

Give a foreign key(primary key of the other entity) to the entity with the side of N,

Question 5

Step 5: Mapping of Binary M:N Relationship Types.

Answer 5

For each regular binary M:N relationship type R, create a new relation S to represent R.
Include as foreign key attributes in S the primary keys of the entities its connected to which is the primary key for this relationship

Question 6

Step 6: Mapping of Multivalued attributes.

Answer 6

Create a new relation, Give it the attribute in the mulitvalued attribute, give it a foreign key to connect it to the Entity

Question 7

Step 7: Mapping of N-ary Relationship Types.

Answer 7

Create new relation, give all primary keys connected to it as a foreign key

Question 8

8A: Multiple relations-Superclass and subclasses.

Answer 8

Create a new relation for the subclasses, give it the primary key of its superclass as a foreign key

Question 9

8B: Multiple relations-Subclass relations only

Answer 9

Give the primary key of the superclass in the subclasses and delete the superclass

Question 10

8C: Single relation with one type attribute.

Answer 10

Add the attributes of all sub-classes to the superclass

Question 11

8D: Single relation with multiple type attributes.

Answer 11

use flags to signify the subclass and add the attributes to the superclass

Question 12

Step 9: Mapping of Union Types (Categories).

Answer 12

Create a surrogate key to place into the superclasses as a foreign key

Question 13

Foreign Key approach:

Answer 13

put a foreign key in both the entities to connect them

Question 14

Merged relation

Answer 14

combine the attributes into one entity

Question 15

Cross-reference

Answer 15

set up a new box for the relationship and place the primary keys of the two entities as foreign keys