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1.3.10. Join types (condition)

  • Theta: Ai q Bj
    (A from R, B from S)
    • q is comparison operator
      =,<,>,!=,>=
    • Ai and Bj share the same domain
  • Equi: Ai = Bj
    • Theta join where q is =
  • Natural: Ai and Bj are the same attribute
    • in two separate relations (name and domain)
    • * denotes natural join
    • e.g. EMPNAMES * DEPENDENTS

Relational join example, equijoin

‹ 1.3.09. Join equivalenceup1.3.11. Join types (inner and outer) ›
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