1.3.06. Relationships in the relational model

  • Two relations, A and B
  • A side, B side, 1 side, N side
  • 1:1 relationships
    • Key can go on either side

Relational model 1 to 1 relationships

  • 1:N relationships
  • Key cannot go on 1 side
  • Has to go on N side

Relational model 1 to N relationships

  • M:N relationships
    • Nowhere obvious for the key to go
    • Create new pairing relation