Database Management Systems

Transcription

1 Database Management Systems Associate Professor Dr. Raed Ibraheem Hamed University of Human Development, College of Science and Technology Computer Science Department and IT

2 First Normal Form (1NF) The term first normal form (1NF) describes the tabular format in which: All the key attributes are defined. There are no repeating groups in the table. All attributes are dependent on the primary key. 2

3 Second Normal Form (2 NF) All attributes dependent on full primary key, partial dependencies and transitive dependencies. Conversion to Second Normal Form Starting with the 1NF format, the database can be converted into the 2NF format by Writing each key component on a separate line, and then writing the original key on the last line and Writing the dependent attributes after each new key. 3

4 Third Normal Form (3 NF) Conversion to Third Normal Form o o All columns can be determined only by the key in the table and no other column. Create a separate table with attributes in a transitive functional dependence relationship. 4

5 Normalization: Overview 1NF (all attributes are atomic) 2NF (no partial dependencies) 3NF (no transitive dependencies) 5 Department of Computer Science and

6 First Normal Form (1NF) First Normal Form (1NF) 1NF: all attributes are atomic ( no repeating groups ) Not in 1NF 6

7 First Normal Form (1NF) Normalized to 1NF 7

8 First Normal Form (1NF) Not in 1NF 8

9 First Normal Form (1NF) Normalized to 1NF 9

10 First Normal Form (1NF) Not in 1NF 10

11 First Normal Form (1NF) Is this relation in 1NF? Formally yes, but in essence, NO! 11

12 First Normal Form (1NF) Normalized to 1NF 12

13 Second Normal Form (2NF) 2NF: 1NF and All non-key attributes are fully dependent on the PK ( no partial dependencies ) Not in 2NF 13

14 Second Normal Form (2NF) Normalized to 2NF 14

15 Second Normal Form (2NF) 15

16 Third Normal Form (3NF) 3NF: 2NF and no transitive dependencies Not in 3NF 16

17 Third Normal Form (3NF) Normalized to 3NF 17

18 Third Normal Form (3NF) 18

19 1 st Normal Form Example Un-normalized Students table: Student# AdvID AdvName AdvRoom Class1 Class A James B Smith Normalized Students table: Student# AdvID AdvName AdvRoom Class# A James A James B Smith B Smith

20 2 nd Normal Form Example Students table Student# AdvID AdvName AdvRoom A James B Smith 467 Registration table Student# Class#

21 3 rd Normal Form Example Students table: Student# AdvID AdvName AdvRoom A James B Smith 467 Student table: Student# AdvID A B Advisor table: AdvID AdvName AdvRoom 123A James B Smith

22 3 rd Normal Form Example Cont. Students table: Student# AdvID A B Registration table: Student# Class# Advisor table: AdvID AdvName AdvRoom 123A James B Smith

23 1 st Normal Form Un-normalized Contacts table: The Zero Form No rules have been applied First Normal Form 1. Eliminate repeating groups in individual tables. 2. Create a separate table for each set of related data. 3. Identify each set of related data with a primary key. 23

24 1 st Normal Form Normalized Contacts table: First Normal Form 24

25 People table: Second Normal Form PhoneNumbers table: Second Normal Form 25

26 Third Normal Form Eliminate fields that do not depend on the primary key Our Company Name, Address and Zip have nothing to do with the PeopleId, so they should have their own AddressId: 26

27 Thank you 27