R R 1 N name age address speciality
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Декомпозиция R R 1 N° name age address speciality 1 A 30 x 1 S 1 2 B 30 x 2 S 2 3 C 30 x 3 S 2 4 D 40 x 4 S 1 âge speciality 30 N name addr S 1 1 A 30 S 2 2 40 S 1 R'=R 1*R 2*R 3 R 2 R 3 N age x 1 1 30 B x 2 2 30 3 C x 3 3 30 4 D x 4 4 40 N° name address age speciality 1 A x 1 30 S 1 1 A x 1 30 S 2 2 B x 2 30 S 1 2 B x 2 30 S 2 3 C x 3 30 S 1 30 S 2 40 S 1 3 4 C x 3 Богдан Шишеджиев - Нормализация D x 4 4
Декомпозиция R R 1 N° name age address speciality 1 A 30 x 1 S 1 2 B 30 x 2 S 2 3 C 30 x 3 S 2 4 D 40 x 4 S 1 N° speciality 1 N name addr S 1 1 A 2 S 2 2 3 S 2 4 S 1 R=R 1*R 2*R 3 R 2 R 3 N age x 1 1 30 B x 2 2 30 3 C x 3 3 30 4 D x 4 4 40 N° name address age speciality 1 A x 1 30 S 1 2 B x 2 30 S 2 3 C x 3 30 S 2 4 D x 4 40 S 1 Богдан Шишеджиев - Нормализация 5
Първа нормална форма • Една релация е в първа нормална форма, ако всичките атрибути съдържат атомарна стойност (базирана върху прост домен) и няма повтарящи се атрибути EMPLOYEЕ (No, name, Child (firstname, age)) EMPLOYEЕ (No, name); CHILDREN( No, firstname, age) No 500 501 510 EMPLOYEE NAME CHILD FIRSTNAME ANDRE 10 JEAN 11 PIERRE 12 PAUL 13 JACQUES 14 DUPONT DURAND LEFEBVRE No 500 501 510 NAME DUPONT DURAND LEFEBVRE CHILDREN Богдан Шишеджиев - Нормализация AGE No 500 501 510 First. Name André Jean Pierre Paul Jacques age 10 11 12 13 14 7
Първа нормална форма MOVIE(No, Name, Director, Actor 1, Actor 2, Actor 3) MOVIE(No, Name, Director) CAST(No. Movie, Actor) MOVIE No Name 1 2 Director Actor 1 Actor 2 The Silence of the Jonathan Lambs Demme Jodie Foster Anthony Hopkins The Sixth Sense Bruce Willis M. Night Shyamalan No Name Director 1 The Silence of the Lambs The Sixth Sense 2 No. Movie Actor Jonathan Demme 1 Jodie Foster M. Night Shyamalan 1 Anthony Hopkins 2 Bruce Willis Богдан Шишеджиев - Нормализация CAST Actor 3 8
Трета нормална форма • Пример CAR (num, mark, type, power, color) color num mark type power Решение 1 R 1(num, type, color) R 2 (type, mark, power) Богдан Шишеджиев - Нормализация Решение 2 R'1(num, type) R'2(num, power, color) R'3 (type, mark) 11
Нормална форма на Бойс-Код INSCRIPTION Course ENG 101 MAT 350 INSCRIPTION Stud Jones Grayson Samara Grayson Jones Berg Course ENG 101 MAT 350 TA Clark Chen Powers O’Shea Powers Stud Jones Grayson Samara Grayson Jones Berg TUTEURS TUTORIAL Course TA ENG 101 Clark ENG 101 Chen MAT 350 Powers MAT 350 O’Shea Stud Jones Grayson Samara Grayson Jones Berg TA Clark Chen Powers O’Shea Powers Декомпозиция Inscription(Cours, Stud) Tutors(Course, TA) Tutorial(Stud, TA) Богдан Шишеджиев - Нормализация 14
Четвърта нормална форма • Многозначни зависимости STUDENTS N COURS SPORT 100 BD Tennis 100 BD Football 200 BD Swimming 200 AN Swimming Y—» Z : x 1 yz 1 et x 2 yz 2 R x 1 yz 2 et x 2 yz 1 R Богдан Шишеджиев - Нормализация 16
Пример за нормализация B C D E a 1 b 1 c 1 d 1 e 1 a 2 b 1 c 1 d 1 e 4 a 1 b 1 c 1 d 2 e 5 a 1 b 3 c 3 d 1 e 2 a 1 b 1 c 1 d 1 e 7 a 1 b 2 c 1 d 1 e 3 a 3 b 1 c 3 d 1 e 6 a 4 b 1 c 1 d 2 e 7 A DE A; EA D; E B; E C; AB C Отговор : T 1(A, D, E) , T 2(A, B, C), T 3(B, E) или T 1(D, E, A), T 2(E, B, C) Богдан Шишеджиев - Нормализация 25
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