Queries: Logical Aspects

• Relational Algebra

  • ?, ?, ?, ?, ?
  • Joins kind of important too!!!
    • General join
    • Equijoin
    • Natural join
  • Transformations for optimization

• SQL

  • Declarative
  • Relational calculus + algebra + grouping, etc.
  • Computationally incomplete
  • Query execution: relational algebra operations

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