1. CCT395, Week 5 Translating ER into Relations; Normalization This presentation is licensed under Creative Commons Attribution License, v. 3.0. To view a copy of this license, visit http://creativecommons.org/licenses/by/3.0/. This presentation incorporates images from the Crystal Clear icon collection by Everaldo Coelho, available under LGPL from http://everaldo.com/crystal/. Yuri Takhteyev University of Toronto October 6, 2010

2. course ---------------------------------------------- -- code title session ---------------------------------------------- -- code start date student ---------------------------------------------- -- last name first name room ---------------------------------------------- -- code capacity building ---------------------------------------------- -- code map url probably redundan t might be redundan t

3. course ---------------------------------------------- -- code title session ---------------------------------------------- -- code start date student ---------------------------------------------- -- last name first name room ---------------------------------------------- -- code capacity building ---------------------------------------------- -- code map url student enrolls in course course is offered in session course meets in room room is in building

4. course ---------------------------------------------- -- code title session ---------------------------------------------- -- code start date room ---------------------------------------------- -- code capacity building ---------------------------------------------- -- code map url student ---------------------------------------------- -- last name first name

5. course ---------------------------------------------- -- code title session ---------------------------------------------- -- code start date student ---------------------------------------------- -- last name first name room ---------------------------------------------- -- code capacity building ---------------------------------------------- -- code map url

6. course ---------------------------------------------- -- code title session ---------------------------------------------- -- code start date student ---------------------------------------------- -- last name first name room ---------------------------------------------- -- code capacity building ---------------------------------------------- -- code map url enrol lmen t

7. course ---------------------------------------------- -- code title session ---------------------------------------------- -- code start date student ---------------------------------------------- -- last name first name room ---------------------------------------------- -- code capacity building ---------------------------------------------- -- code map url enrol lmen t

8. course ---------------------------------------------- -- code title session ---------------------------------------------- -- code start date student ---------------------------------------------- -- last name first name room ---------------------------------------------- -- code capacity building ---------------------------------------------- -- code map url enrol lmen t cours e insta nce

9. course ---------------------------------------------- -- code title session ---------------------------------------------- -- code start date student ---------------------------------------------- -- last name first name room ---------------------------------------------- -- code capacity building ---------------------------------------------- -- code map url enrol lmen t cours e insta nce

10. course ---------------------------------------------- -- code title session ---------------------------------------------- -- code start date student ---------------------------------------------- -- last name first name room ---------------------------------------------- -- code capacity building ---------------------------------------------- -- code map url enrol lmen t cours e insta nce

11. course ---------------------------------------------- -- code title session ---------------------------------------------- -- code start date student ---------------------------------------------- -- last name first name room ---------------------------------------------- -- code capacity building ---------------------------------------------- -- code map url enrol lmen t cours e insta nce

12. course ---------------------------------------------- -- code title session ---------------------------------------------- -- code start date student ---------------------------------------------- -- last name first name room ---------------------------------------------- -- code capacity building ---------------------------------------------- -- code map url enrol lmen t cours e insta nce

13. course ---------------------------------------------- -- code title session ---------------------------------------------- -- code start date student ---------------------------------------------- -- last name first name room ---------------------------------------------- -- code capacity building ---------------------------------------------- -- code map url enrollment ---------------------------------------------- -- course instance ---------------------------------------------- -- final exam?

14. course ---------------------------------------------- -- code title session ---------------------------------------------- -- code start date student ---------------------------------------------- -- last name first name room ---------------------------------------------- -- code capacity building ---------------------------------------------- -- code map url enrollment ---------------------------------------------- -- course instance ---------------------------------------------- -- final exam?

15. Step 1 “Create one table for each entity” (after breaking up M:M)

16. student ------------------------------------------------ last name first name student

17. ------------------------------------------------ last name first name student

18. ------------------------------------------------ last name first name student

19. ------------------------------------------------ last name first name student

20. (do this for every entity)

21. Step 2 “For each entity that is only on the ‘one’ end of one or more relationships and not at the ‘many’ end of any relationship, create a single-column primary key... if no natural primary key is available.”

22. Step 2 “For each entity that is only on the ‘one’ end of one or more relationships and not at the ‘many’ end of any relationship, create a single-column primary key... if no natural primary key is available.”

23. course ---------------------------------------------- -- code title session ---------------------------------------------- -- code start date student ---------------------------------------------- -- last name first name room ---------------------------------------------- -- code capacity building ---------------------------------------------- -- code map url enrollment ---------------------------------------------- -- course instance ---------------------------------------------- -- final exam?

24. course ---------------------------------------------- -- code title session ---------------------------------------------- -- code start date student ---------------------------------------------- -- last name first name room ---------------------------------------------- -- code capacity building ---------------------------------------------- -- code map url enrollment ---------------------------------------------- -- course instance ---------------------------------------------- -- final exam?

25. course ---------------------------------------------- -- code title session ---------------------------------------------- -- code start date student ---------------------------------------------- -- last name first name room ---------------------------------------------- -- code capacity building ---------------------------------------------- -- code map url enrollment ---------------------------------------------- -- course instance ---------------------------------------------- -- final exam?

26. course ---------------------------------------------- -- code title session ---------------------------------------------- -- code start date student ---------------------------------------------- -- last name first name room ---------------------------------------------- -- code capacity building ---------------------------------------------- -- code map url enrollment ---------------------------------------------- -- course instance ---------------------------------------------- -- final exam?

27. course ---------------------------------------------- -- code title session ---------------------------------------------- -- code start date student ---------------------------------------------- -- last name first name room ---------------------------------------------- -- code capacity building ---------------------------------------------- -- code map url enrollment ---------------------------------------------- -- course instance ---------------------------------------------- -- final exam?

28. Step 2 “For each entity that is only on the ‘one’ end of one or more relationships and not at the ‘many’ end of any relationship, create a single-column primary key... if no natural primary key is available.”

29. Keys no key! student

30. Keys a candidate key student

31. Keys another candidate key student

32. Keys candidate #1 student candidate #2

33. Keys candidate #1 student candidate #2 candidate #1 primary key

34. Multi-Column Keys city a key!

35. Multi-Column Keys city a three column key

36. Multi-Column Keys city candidate #1 candidate #2

37. Step 2 “For each entity that is only on the ‘one’ end of one or more relationships and not at the ‘many’ end of any relationship, create a single-column primary key... if no natural primary key is available.”

38. student

39. let’s add it student

41. course ---------------------------------------------- -- code title session ---------------------------------------------- -- code start date student ---------------------------------------------- -- last name first name room ---------------------------------------------- -- code capacity building ---------------------------------------------- -- code map url enrollment ---------------------------------------------- -- course instance ---------------------------------------------- -- final exam?

42. course ---------------------------------------------- -- code* title session ---------------------------------------------- -- code* start date student ---------------------------------------------- -- last name first name student_id* room ---------------------------------------------- -- code capacity building ---------------------------------------------- -- code* map url enrollment ---------------------------------------------- -- course instance ---------------------------------------------- -- final exam?

43. course ---------------------------------------------- -- code title course_id* session ---------------------------------------------- -- code start date session_id* student ---------------------------------------------- -- last name first name student_id* room ---------------------------------------------- -- code capacity building ---------------------------------------------- -- code map url building_id* enrollment ---------------------------------------------- -- course instance ---------------------------------------------- -- final exam?

44. Step 3 “For each entity that is at the ‘many’ end of one or more relationships, include the primary key of each parent entity in the table as foreign keys.”

45. Step 3 “For each entity that is at the ‘many’ end of one or more relationships, include the primary key of each parent entity in the table as foreign keys.”

46. course ---------------------------------------------- -- code title course_id* session ---------------------------------------------- -- code start date session_id* student ---------------------------------------------- -- last name first name student_id* room ---------------------------------------------- -- code capacity building ---------------------------------------------- -- code map url building_id* enrollment ---------------------------------------------- -- course instance ---------------------------------------------- -- final exam?

47. course ---------------------------------------------- -- code title course_id* session ---------------------------------------------- -- code start date session_id student ---------------------------------------------- -- last name first name student_id* room ---------------------------------------------- -- code capacity building ---------------------------------------------- -- code map url building_id* enrollment ---------------------------------------------- -- course instance ---------------------------------------------- -- final exam?

48. Step 3 “For each entity that is at the ‘many’ end of one or more relationships, include the primary key of each parent entity in the table as foreign keys.”

49. course ---------------------------------------------- -- code title course_id* session ---------------------------------------------- -- code start date session_id* student ---------------------------------------------- -- last name first name student_id* room ---------------------------------------------- -- code capacity building ---------------------------------------------- -- code map url building_id* enrollment ---------------------------------------------- -- course instance ---------------------------------------------- -- final exam?

50. course ---------------------------------------------- -- code title course_id* session ---------------------------------------------- -- code start date session_id student ---------------------------------------------- -- last name first name student_id* room ---------------------------------------------- -- code capacity building ---------------------------------------------- -- code map url building_id* enrollment ---------------------------------------------- -- course instance ---------------------------------------------- -- final exam?

51. course ---------------------------------------------- -- code title course_id* session ---------------------------------------------- -- code start date session_id* student ---------------------------------------------- -- last name first name student_id* room ---------------------------------------------- -- code capacity building ---------------------------------------------- -- code map url building_id* enrollment ---------------------------------------------- -- course instance ---------------------------------------------- -- final exam?

52. course ---------------------------------------------- -- code title course_id* session ---------------------------------------------- -- code start date session_id* student ---------------------------------------------- -- last name first name student_id* room ---------------------------------------------- -- code capacity building_id building ---------------------------------------------- -- code map url building_id* enrollment ---------------------------------------------- -- student_id course instance ---------------------------------------------- -- final exam? course_id session_id

53. course ---------------------------------------------- -- code title course_id* session ---------------------------------------------- -- code start date session_id* student ---------------------------------------------- -- last name first name student_id* room ---------------------------------------------- -- code capacity building_id building ---------------------------------------------- -- code map url building_id* enrollment ---------------------------------------------- -- student_id course instance ---------------------------------------------- -- final exam? course_id session_id

54. Step 4a “If an entity at the ‘many’ end of one or more relationships, has a natural primary key, use that single key as a the primary key.”

55. course ---------------------------------------------- -- code title course_id* session ---------------------------------------------- -- code start date session_id* student ---------------------------------------------- -- last name first name student_id* room ---------------------------------------------- -- code capacity building_id building ---------------------------------------------- -- code map url building_id* enrollment ---------------------------------------------- -- student_id course instance ---------------------------------------------- -- final exam? course_id session_id

56. Step 4b “Otherwise, concatenate the primary key of its parent with any other column or columns needed for uniqueness to form the table’s primary key.”

57. course ---------------------------------------------- -- code title course_id* session ---------------------------------------------- -- code start date session_id* student ---------------------------------------------- -- last name first name student_id* room ---------------------------------------------- -- code capacity building_id building ---------------------------------------------- -- code map url building_id* enrollment ---------------------------------------------- -- student_id course instance ---------------------------------------------- -- final exam? course_id session_id

58. Step 4c If necessary, add a field!

59. course ---------------------------------------------- -- code title course_id* session ---------------------------------------------- -- code start date session_id* student ---------------------------------------------- -- last name first name student_id* room ---------------------------------------------- -- code capacity building_id room_id* building ---------------------------------------------- -- code map url building_id* enrollment ---------------------------------------------- -- student_id course instance ---------------------------------------------- -- final exam? course_id session_id

60. course ---------------------------------------------- -- code title course_id* session ---------------------------------------------- -- code start date session_id* student ---------------------------------------------- -- last name first name student_id* room ---------------------------------------------- -- code capacity building_id room_id* building ---------------------------------------------- -- code map url building_id* enrollment ---------------------------------------------- -- student_id course instance ---------------------------------------------- -- final exam? course_id session_id

61. Step 4d Go back to step 3!

62. course ---------------------------------------------- -- code title course_id* session ---------------------------------------------- -- code start date session_id* student ---------------------------------------------- -- last name first name student_id* room ---------------------------------------------- -- code capacity building_id room_id* building ---------------------------------------------- -- code map url building_id* enrollment ---------------------------------------------- -- student_id course instance ---------------------------------------------- -- final exam? course_id session_id room_id

63. course ---------------------------------------------- -- code title course_id* session ---------------------------------------------- -- code start date session_id* student ---------------------------------------------- -- last name first name student_id* room ---------------------------------------------- -- code capacity building_id room_id* building ---------------------------------------------- -- code map url building_id* enrollment ---------------------------------------------- -- student_id course instance ---------------------------------------------- -- final exam? course_id* session_id* room_id*

64. course ---------------------------------------------- -- code title course_id* session ---------------------------------------------- -- code start date session_id* student ---------------------------------------------- -- last name first name student_id* room ---------------------------------------------- -- code capacity building_id room_id* building ---------------------------------------------- -- code map url building_id* enrollment ---------------------------------------------- -- student_id course instance ---------------------------------------------- -- final exam? course_id* session_id* room_id*

65. course ---------------------------------------------- -- code title course_id* session ---------------------------------------------- -- code start date session_id* student ---------------------------------------------- -- last name first name student_id* room ---------------------------------------------- -- code capacity building_id room_id* building ---------------------------------------------- -- code map url building_id* enrollment ---------------------------------------------- -- student_id* instance_id * course instance ---------------------------------------------- -- final exam? course_id session_id room_id instance_id*

66. course ---------------------------------------------- -- code title course_id* session ---------------------------------------------- -- code start date session_id* student ---------------------------------------------- -- last name first name student_id* room ---------------------------------------------- -- code capacity building_id room_id* building ---------------------------------------------- -- code map url building_id* enrollment ---------------------------------------------- -- student_id* instance_id* course instance ---------------------------------------------- -- final exam? course_id session_id room_id instance_id*

67. course_instance

68. course ---------------------------------------------- -- code title course_id* session ---------------------------------------------- -- code start date session_id* student ---------------------------------------------- -- last name first name student_id* room ---------------------------------------------- -- code capacity building_id room_id* building ---------------------------------------------- -- code map url building_id* enrollment ---------------------------------------------- -- student_id* instance_id* course instance ---------------------------------------------- -- final exam? course_id session_id room_id instance_id*

69. course_instance

70. Step 5 Normalize!

71. Normalization Checking that the table does not have any well-known problems

72. What Problems?

73. Normal Forms 4 th Normal Form BC Normal Form 3 rd Normal Form 2 nd Normal Form 1 st Normal Form 5 th Normal Form trivial! you can do it! fixing weird issues

74. 1NF No multi-valued attributes

76. The Wrong Solution

77. The Right Solution

78. 2NF and 3NF Getting rid of “functional dependencies”

79. course title grade code student id course id student name “Each attribute must describe the key, grade points the whole key, and nothing but the key.” “So help me Codd!”

80. course title grade code student id course id student name “Each attribute must describe the key... grade points

81. course title grade code student id course id student name “Each attribute must describe the key, the whole key, and nothing but the key.” grade points partial dependency full dependency transitive dependency “So help me Codd!”

82. 2NF: no partial dependencies (“the whole key”) 3NF: 2NF + no transitive dependencies (“nothing but the key”) 2NF and 3NF

83. Reaching 2NF and 3NF Decomposition (break up tables into several)

84. course title grade code student id course id student name grade points

85. course course title grade code student id course id student name course id student id grade points

86. course course title grade code student id course id student name grade points grade code course id student id

87. “all determinants must be candidate keys” BCNF

88. course time slot instructor id room id course code overlapping candidate keys

89. course time slot instructor id room id dependencies between keys

90. course time slot instructor id room id dependencies between keys

91. course time slot instructor id instructor utorid this is 3NF, but not BCNF (“so help me Codd”)

92. course time slot instructor id instructor utorid decompose it instructor id

93. course course id project id student id some relations cannot be decomposed into BCNF (“so help me Codd”) student, course → project project → course

94. Mistaking binary relationships for ternary 4NF

95. course ---------------------------------------------- -- code title session ---------------------------------------------- -- code start date room ---------------------------------------------- -- code capacity

96. course ---------------------------------------------- -- code title session ---------------------------------------------- -- code start date room ---------------------------------------------- -- code capacity cours e insta nce

97. student ---------------------------------------------- -- job ------------------------------------------------ course ------------------------------------------------

98. 5NF “We could break it up yet more”

99. Questions?