Databases

Question

How to identify many to many relationship.

Can R2 be one to one.

Comments

Many to Many Relationships would not have any arrows at either end. Since R2 relationship doesn't have any such arrows on either end it is a Many to Many Relationship

---

@Sunnidhya Roy

any reference

---

@GateOverflow04 you can refer to this link The Entity-Relationship Model (juniata.edu), Scroll down to Cardinality of Relationships, there can be various representations for 1 to 1, 1 to Many, Many to Many, some of the popular ones are listed there.

---

Why are min. 4 foreign keys required?