EERM to RM

Question 1

Step 1: Mapping of Regular entity types

Answer 1

Create a relation that includes all the attributes of the entity;
Choose one of the key attributes to be a key attribute in the relation

Question 2

Step 2: Mapping of Weak-entity types

Answer 2

Create a relation, add attributes,;
Include primary key of owner as foreign key;
Primary key is combination of foreign key and partial key

Question 3

Step 3: Mapping of binary 1:1 relationship

Answer 3

Create a relation for the relationship (if needed);
Choose one of the relations and include a foreign key in that relation

Question 4

Step 4: Mapping of 1:N relationships

Answer 4

Create a relation for the relationship (if needed);
Include primary key of 1 side as foreign key of N side

Question 5

Step 5: Mapping of M:N relationships

Answer 5

Create a relation for the relationship;
Include the primary keys of both sides in the relation

Question 6

Step 6: Mapping of multivalued attributes

Answer 6

Create a relation for the attribute;
Use primary key of the main entity;
Primary key will be primary key from main entity and name of multivalued attribute

Question 7

Step 7: Mapping of Composite attributes

Answer 7

Create a relation for the attribute (if needed);
Use primary key of the main entity;
Primary key will be primary key from main entity and attributes of the composite attribute

Question 8

Step 8: Mapping of N-ary relationships

Answer 8

Create a relation for the relationship;
Add the simple attributes

Question 9

Multiple relations - Superclass and Subclasses

Answer 9

Create a relation L for the super class. Create a separate relation for each subclass, where the primary key for each relation is the primary key of the superclass