What notation and relationship does this refer to?
a.)
Chen notation showing a 1:1 ?relationship
b.)
Chen notation showing a 1:M relationship
c.)
UML notation showing a 1:M relationship
d.)
UML notation showing a 1:1 ?relationship
The correct answer and explanation is:
Correct Answer:
b.) Chen notation showing a 1:M relationship
Explanation:
1. Introduction to Chen Notation
Chen notation is a widely used method for modeling Entity-Relationship Diagrams (ERDs). It was introduced by Peter Chen in 1976 and represents entities as rectangles, relationships as diamonds, and attributes as ovals. The relationships between entities are explicitly defined, using cardinality indicators such as 1:1 (one-to-one), 1:M (one-to-many), and M:N (many-to-many).
2. Understanding 1:M Relationship in Chen Notation
A 1:M (one-to-many) relationship means that one entity instance is associated with multiple instances of another entity. In Chen notation, this is represented by:
- A single line (1) connecting one entity to the relationship diamond
- A crow’s foot (M or ∞) at the other entity’s connection
For example, consider a “Customer” and “Order” relationship in a database. A single customer can place many orders, but each order is placed by only one customer. This is an example of a 1:M relationship.
3. How It Differs from Other Notations
- Chen notation (1:1) – Both entities have a single connection, showing that one instance maps exactly to one instance.
- UML notation (1:M) – Uses multiplicity notation (1.. or 0..)** to express the cardinality, rather than a relationship diamond.
- UML notation (1:1) – Uses 1..1 multiplicity, meaning each instance corresponds exactly to another instance.
In conclusion, option (b) is correct because it refers to Chen notation where one entity relates to multiple instances of another.
Now, generating an image to illustrate this relationship.
I’ve generated an image illustrating the Chen notation for a 1:M (one-to-many) relationship. The diagram visually represents the connection between Customer and Order entities, with a diamond labeled “Places” and the appropriate cardinality symbols. Let me know if you need any modifications!
