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Database Normalization
The document discusses database normalization. It defines three normal forms: first normal form requires each cell to contain a single value and records to be unique; second normal form requires all non-key fields to depend on the whole primary key; third normal form requires all non-key fields to depend only on the primary key. An example shows a database normalized to third normal form, with the postal code moved to its own table since other fields depend on it rather than just the primary key. The summary is to normalize data such that all non-key columns depend only on the primary key.
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Database Normalization
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- 2. NORMALIZATION?? • In RDBs>> For Transactional Purpose >> We Need to minimum the redundancy • In Insert • In Update • In Deletion • Result in: • Consistency • Performance
- 3. FIRST NORMAL FORM •Each cell contains only a single value. • Each record is unique. • Identified by primary key
- 4. EXAMPLE? Name SSN AddressPostal code Ehsan Hamzei 3920221621 N435 Test alley, Test St, Test Sq, Tehran, Iran 231233213 Ali Hashemi 3242342432 N2131 Work alley, Work St, Work Sq, Mashhad, Iran 324234234 Hassan Mohammadi 2342342344 N2332 Home alley, Home St, Home Sq, LA, USA 324124234
- 5. EXAMPLE? Name SSN AddressPostal code Ehsan Hamzei 3920221621 N435 Test alley, Test St, Test Sq, Tehran, Iran 231233213 Ali Hashemi 3242342432 N2131 Work alley, Work St, Work Sq, Mashhad, Iran 324234234 Hassan Mohammadi 2342342344 N2332 Home alley, Home St, Home Sq, LA, USA 324124234
- 6. EXAMPLE? • Violated !!! •First Name , Last Name • Address >> Building Number, Alley Name, Street Name, Locality, City, Country • PK: SSN
- 7. EXAMPLE? • Normalized (FirstNormal Form) FN LN SSN BN AN SN LN City Country Postal code Ehsan Hamzei 3920221621 N435 Test alley Test St Test Sq Tehran Iran 2312332 13 Ali Hashemi 3242342432 N2131 Work alley Work St Work Sq Mashhad Iran 3242342 34 Hassan Mohamm adi 2342342344 N2332 Home alley Home St Home Sq LA USA 3241242 34
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- 10. SECOND NORMAL FORM •Must be first normal! • All non-key fields depend on all components of the primary key. • Guaranteed when primary key is a single field.
- 11. EXAMPLE • This exampleis normal in (2nd NF), Because of the single component key!!!!! FN LN SSN BN AN SN LN City Country Postal code Ehsan Hamzei 3920221621 N435 Test alley Test St Test Sq Tehran Iran 2312332 13 Ali Hashemi 3242342432 N2131 Work alley Work St Work Sq Mashhad Iran 3242342 34 Hassan Mohamm adi 2342342344 N2332 Home alley Home St Home Sq LA USA 3241242 34
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- 14. THIRD NORMAL FORM •No non-key field depends upon another. • All non-key fields depend only on the primary key.
- 15. EXAMPLE??? FN LN SSNBN AN SN LN City Country Postal code Ehsan Hamzei 3920221621 N435 Test alley Test St Test Sq Tehran Iran 2312332 13 Ali Hashemi 3242342432 N2131 Work alley Work St Work Sq Mashhad Iran 3242342 34 Hassan Mohamm adi 2342342344 N2332 Home alley Home St Home Sq LA USA 3241242 34
- 16. EXAMPLE??? • Violated !!! •Country & City & LN & SN & BN depend on Postal Code!!!
- 17. EXAMPLE FN LN SSNPostal Code Ehsan Hamzei 3920221621 231233213 Ali Hashemi 3242342432 324234234 Hassan Mohammadi 2342342344 324321234 Postal Code BN AN SN LN City Country 2312332 13 N435 Test Alley Test St Test Sq Tehran Iran 3242342 34 N2131 Work Allry Work St Work Sq Mashha d Iran 3241242 34 N2332 Home Alley Home St Home Sq LA USA
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- 21. SUMMARY •All Non-Key Columnmust depend on PK, All Part of PK and Only on PK!!!!!!
- 22. REFERENCE • Data-Base Design(Practical Database Design for Relational Database Management Systems) • Instructional Services at KU Libraries, The University of Kansas
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