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Carnegie Mellon Univ. Dept. of Computer Science 15-415 - Database Applications

Carnegie Mellon Univ. Dept. of Computer Science 15-415 - Database Applications. C. Faloutsos Relational domain calculus. General Overview. relational model Formal query languages relational algebra rel. tuple calculus rel. domain calculus. Overview - detailed. rel. tuple calculus dfn

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Carnegie Mellon Univ. Dept. of Computer Science 15-415 - Database Applications

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  1. Carnegie Mellon Univ.Dept. of Computer Science15-415 - Database Applications C. Faloutsos Relational domain calculus

  2. General Overview • relational model • Formal query languages • relational algebra • rel. tuple calculus • rel. domain calculus 15-415 - C. Faloutsos

  3. Overview - detailed • rel. tuple calculus • dfn • details • equivalence to rel. algebra • rel. domain calculus + QBE 15-415 - C. Faloutsos

  4. Rel. domain calculus (RDC) • Q: why? • A: slightly easier than RTC, although equivalent - basis for QBE. • idea: domain variables (w/ F.O.L.) - eg: • ‘find STUDENT record with ssn=123’ 15-415 - C. Faloutsos

  5. Rel. Dom. Calculus • find STUDENT record with ssn=123’ 15-415 - C. Faloutsos

  6. Details • Like R.T.C - symbols allowed: • quantifiers 15-415 - C. Faloutsos

  7. Details • but: domain (= column) variables, as opposed to tuple variables, eg: ssn address name 15-415 - C. Faloutsos

  8. Reminder: our Mini-U db 15-415 - C. Faloutsos

  9. Examples • find all student records RTC: 15-415 - C. Faloutsos

  10. Examples • (selection) find student record with ssn=123 15-415 - C. Faloutsos

  11. Examples • (selection) find student record with ssn=123 or RTC: 15-415 - C. Faloutsos

  12. Examples • (projection) find name of student with ssn=123 15-415 - C. Faloutsos

  13. Examples • (projection) find name of student with ssn=123 need to ‘restrict’ “a” RTC: 15-415 - C. Faloutsos

  14. Examples cont’d • (union) get records of both PT and FT students RTC: 15-415 - C. Faloutsos

  15. Examples cont’d • (union) get records of both PT and FT students 15-415 - C. Faloutsos

  16. Examples • difference: find students that are not staff RTC: 15-415 - C. Faloutsos

  17. Examples • difference: find students that are not staff 15-415 - C. Faloutsos

  18. Cartesian product • eg., dog-breeding: MALE x FEMALE • gives all possible couples = x 15-415 - C. Faloutsos

  19. Cartesian product • find all the pairs of (male, female) - RTC: 15-415 - C. Faloutsos

  20. Cartesian product • find all the pairs of (male, female) - RDC: 15-415 - C. Faloutsos

  21. ‘Proof’ of equivalence • rel. algebra <-> rel. domain calculus <-> rel. tuple calculus 15-415 - C. Faloutsos

  22. Overview - detailed • rel. domain calculus • why? • details • examples • equivalence with rel. algebra • more examples; ‘safety’ of expressions 15-415 - C. Faloutsos

  23. More examples • join: find names of students taking 15-415 15-415 - C. Faloutsos

  24. Reminder: our Mini-U db 15-415 - C. Faloutsos

  25. More examples • join: find names of students taking 15-415 - in RTC 15-415 - C. Faloutsos

  26. More examples • join: find names of students taking 15-415 - in RDC 15-415 - C. Faloutsos

  27. Sneak preview of QBE: 15-415 - C. Faloutsos

  28. Sneak preview of QBE: • very user friendly • heavily based on RDC • very similar to MS Access interface 15-415 - C. Faloutsos

  29. More examples • 3-way join: find names of students taking a 2-unit course - in RTC: join projection selection 15-415 - C. Faloutsos

  30. Reminder: our Mini-U db _x .P _y 2 _x _y 15-415 - C. Faloutsos

  31. More examples • 3-way join: find names of students taking a 2-unit course 15-415 - C. Faloutsos

  32. More examples • 3-way join: find names of students taking a 2-unit course 15-415 - C. Faloutsos

  33. Even more examples: • self -joins: find Tom’s grandparent(s) 15-415 - C. Faloutsos

  34. Even more examples: • self -joins: find Tom’s grandparent(s) 15-415 - C. Faloutsos

  35. Even more examples: • self -joins: find Tom’s grandparent(s) 15-415 - C. Faloutsos

  36. Even more examples: • self -joins: find Tom’s grandparent(s) 15-415 - C. Faloutsos

  37. Hard examples: DIVISION • find suppliers that shipped all the ABOMB parts 15-415 - C. Faloutsos

  38. Hard examples: DIVISION • find suppliers that shipped all the ABOMB parts 15-415 - C. Faloutsos

  39. Hard examples: DIVISION • find suppliers that shipped all the ABOMB parts 15-415 - C. Faloutsos

  40. More on division • find students that take all the courses that ssn=123 does (and maybe even more) 15-415 - C. Faloutsos

  41. More on division • find students that take all the courses that ssn=123 does (and maybe even more) 15-415 - C. Faloutsos

  42. Safety of expressions • similar to RTC • FORBIDDEN: 15-415 - C. Faloutsos

  43. Overview - detailed • rel. domain calculus + QBE • dfn • details • equivalence to rel. algebra 15-415 - C. Faloutsos

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