Normalization PRESENTATION
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Database normalization is the process of organizing data in tables to minimize redundancy and dependency. It involves splitting tables into smaller tables and defining relationships between them using primary and foreign keys. There are various normal forms that quantify how normalized a database is, with third normal form being sufficient for most applications. Edgar Codd first proposed normalization and the first normal form, which requires that tables have a primary key and each attribute depend on the key. Higher normal forms like second and third further reduce redundancy between columns and tables.
Normalization PRESENTATION
- 1. NormalizationNormalization By Amit KumarBy Amit Kumar
- 2. Database NormalizationDatabase Normalization Database normalizationDatabase normalization is the process of removingis the process of removing redundant data from your tables in to improve storageredundant data from your tables in to improve storage efficiency, data integrity, and scalability.efficiency, data integrity, and scalability. In the relational model, methods exist for quantifying howIn the relational model, methods exist for quantifying how efficient a database is. These classifications are calledefficient a database is. These classifications are called normal formsnormal forms (or(or NFNF), and there are algorithms for), and there are algorithms for converting a given database between them.converting a given database between them. Normalization generally involves splitting existing tablesNormalization generally involves splitting existing tables into multiple ones, which must be re-joined or linkedinto multiple ones, which must be re-joined or linked each time a query is issued.each time a query is issued.
- 3. HistoryHistory Edgar F. Codd first proposed the process ofEdgar F. Codd first proposed the process of normalization and what came to be known asnormalization and what came to be known as thethe 1st normal form1st normal form in his paperin his paper A RelationalA Relational Model of Data for Large Shared Data BanksModel of Data for Large Shared Data Banks Codd stated:Codd stated: ““There is, in fact, a very simple eliminationThere is, in fact, a very simple elimination procedure which we shall call normalization.procedure which we shall call normalization. Through decomposition nonsimple domains areThrough decomposition nonsimple domains are replaced by ‘replaced by ‘domains whose elements aredomains whose elements are atomic (nondecomposable) values.’”atomic (nondecomposable) values.’”
- 4. Normal FormNormal Form Edgar F. Codd originally established threeEdgar F. Codd originally established three normal forms: 1NF, 2NF and 3NF. Therenormal forms: 1NF, 2NF and 3NF. There are now others that are generallyare now others that are generally accepted, but 3NF is widely considered toaccepted, but 3NF is widely considered to be sufficient for most applications. Mostbe sufficient for most applications. Most tables when reaching 3NF are also intables when reaching 3NF are also in BCNF (Boyce-Codd Normal Form).BCNF (Boyce-Codd Normal Form).
- 5. Table 1Table 1 TitleTitle Author1Author1 AuthorAuthor 22 ISBNISBN SubjectSubject PagesPages PublisherPublisher DatabaseDatabase SystemSystem ConceptsConcepts AbrahamAbraham SilberschatzSilberschatz HenryHenry F. KorthF. Korth 00729588630072958863 MySQL,MySQL, ComputersComputers 11681168 McGraw-HillMcGraw-Hill OperatingOperating SystemSystem ConceptsConcepts AbrahamAbraham SilberschatzSilberschatz HenryHenry F. KorthF. Korth 04716946650471694665 ComputersComputers 944944 McGraw-HillMcGraw-Hill
- 6. Table 1 problemsTable 1 problems This table is not very efficient with storage.This table is not very efficient with storage. This design does not protect data integrity.This design does not protect data integrity. Third, this table does not scale well.Third, this table does not scale well.
- 7. First Normal FormFirst Normal Form In our Table 1, we have two violations ofIn our Table 1, we have two violations of First Normal Form:First Normal Form: First, we have more than one author field,First, we have more than one author field, Second, our subject field contains moreSecond, our subject field contains more than one piece of information. With morethan one piece of information. With more than one value in a single field, it would bethan one value in a single field, it would be very difficult to search for all books on avery difficult to search for all books on a given subject.given subject.
- 8. First Normal TableFirst Normal Table Table 2Table 2 TitleTitle AuthorAuthor ISBNISBN SubjectSubject PagesPages PublisherPublisher Database SystemDatabase System ConceptsConcepts AbrahamAbraham SilberschatzSilberschatz 00729588630072958863 MySQLMySQL 11681168 McGraw-HillMcGraw-Hill Database SystemDatabase System ConceptsConcepts Henry F. KorthHenry F. Korth 00729588630072958863 ComputersComputers 11681168 McGraw-HillMcGraw-Hill Operating SystemOperating System ConceptsConcepts Henry F. KorthHenry F. Korth 04716946650471694665 ComputersComputers 944944 McGraw-HillMcGraw-Hill Operating SystemOperating System ConceptsConcepts AbrahamAbraham SilberschatzSilberschatz 04716946650471694665 ComputersComputers 944944 McGraw-HillMcGraw-Hill
- 9. We now have two rows for a single book.We now have two rows for a single book. Additionally, we would be violating theAdditionally, we would be violating the Second Normal Form…Second Normal Form… A better solution to our problem would beA better solution to our problem would be to separate the data into separate tables-to separate the data into separate tables- an Author table and a Subject table toan Author table and a Subject table to store our information, removing thatstore our information, removing that information from the Book table:information from the Book table:
- 10. Subject_IDSubject_ID SubjectSubject 11 MySQLMySQL 22 ComputersComputers Author_IDAuthor_ID Last NameLast Name First NameFirst Name 11 SilberschatzSilberschatz AbrahamAbraham 22 KorthKorth HenryHenry ISBNISBN TitleTitle PagesPages PublisherPublisher 00729588630072958863 Database SystemDatabase System ConceptsConcepts 11681168 McGraw-HillMcGraw-Hill 04716946650471694665 Operating SystemOperating System ConceptsConcepts 944944 McGraw-HillMcGraw-Hill Subject Table Author Table Book Table
- 11. Each table has a primary key, used forEach table has a primary key, used for joining tables together when querying thejoining tables together when querying the data. A primary key value must be uniquedata. A primary key value must be unique with in the table (no two books can havewith in the table (no two books can have the same ISBN number), and a primarythe same ISBN number), and a primary key is also an index, which speeds upkey is also an index, which speeds up data retrieval based on the primary key.data retrieval based on the primary key. Now to define relationships between theNow to define relationships between the tablestables
- 12. RelationshipsRelationships ISBNISBN Author_IDAuthor_ID 00729588630072958863 11 00729588630072958863 22 04716946650471694665 11 04716946650471694665 22 ISBNISBN Subject_IDSubject_ID 00729588630072958863 11 00729588630072958863 22 04716946650471694665 22 Book_Author Table Book_Subject Table
- 13. Second Normal FormSecond Normal Form As the First Normal Form deals with redundancyAs the First Normal Form deals with redundancy of data across a horizontal row, Second Normalof data across a horizontal row, Second Normal Form (or 2NF) deals with redundancy of data inForm (or 2NF) deals with redundancy of data in vertical columns.vertical columns. As stated earlier, the normal forms areAs stated earlier, the normal forms are progressive, so to achieve Second Normalprogressive, so to achieve Second Normal Form, the tables must already be in First NormalForm, the tables must already be in First Normal Form.Form. The Book Table will be used for the 2NFThe Book Table will be used for the 2NF exampleexample
- 14. 2NF Table2NF Table Publisher_IDPublisher_ID Publisher NamePublisher Name 11 McGraw-HillMcGraw-Hill ISBNISBN TitleTitle PagesPages Publisher_IDPublisher_ID 00729588630072958863 Database SystemDatabase System ConceptsConcepts 11681168 11 04716946650471694665 Operating SystemOperating System ConceptsConcepts 944944 11 Publisher Table Book Table
- 15. 2NF2NF Here we have a one-to-many relationshipHere we have a one-to-many relationship between the book table and the publisher. Abetween the book table and the publisher. A book has only one publisher, and a publisher willbook has only one publisher, and a publisher will publish many books. When we have a one-to-publish many books. When we have a one-to- many relationship, we place a foreign key in themany relationship, we place a foreign key in the Book Table, pointing to the primary key of theBook Table, pointing to the primary key of the Publisher Table.Publisher Table. The other requirement for Second Normal FormThe other requirement for Second Normal Form is that you cannot have any data in a table with ais that you cannot have any data in a table with a composite key that does not relate to all portionscomposite key that does not relate to all portions of the composite key.of the composite key.
- 16. Third Normal FormThird Normal Form Third normal form (3NF) requires thatThird normal form (3NF) requires that there are no functional dependencies ofthere are no functional dependencies of non-key attributes on something othernon-key attributes on something other than a candidate key.than a candidate key. A table is in 3NF if all of the non-primaryA table is in 3NF if all of the non-primary key attributes are mutually independentkey attributes are mutually independent There should not be transitiveThere should not be transitive dependenciesdependencies
- 17. Boyce-Codd Normal FormBoyce-Codd Normal Form BCNF requires that the table is 3NF andBCNF requires that the table is 3NF and only determinants are the candidate keysonly determinants are the candidate keys
- 18. ENDEND