updated: 2022-01-23_12:32:31-05:00

Review Difficult Questions for HW 1 - Relational Algebra

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2.4.1

  • f: HD the same, but model the not (pc crossed with itself)
  • g: we can remove the not equal to and replace with less than
  • i: compare computers with itself, subtract slow ones from table (slow ones are speed1<speed2)
  • j: cross three times and select speed1 <> speed2 <> speed3
  • k: cross three times select model1 <> model2 <> model3