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Normalization

Connolly BookChapter 14-15

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Normalization

• What is Normalization?– Normalization is a technique for producing a set of relations with

desirable properties, given the data requirements of an enterprise.

• The purpose of Normalization is to make a suitable set of relations to support data requirements of an enterprise.

• What is suitable set of relations?– Minimum redundancy– Attributes in a relation must have functional dependency– Minimum number of attribute

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Redundancy

• Redundancy in database happens when we copy the primary keys from a parent/strong entity to child/weak entity.

• If we copy more than the primary key, redundancy will make problems called update anomalies.

• Update anomalies consist of – Insertion anomalies.– Deletion anomalies.– and modification anomalies.

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Insertion Anomalies

StudentsProdi

• Two types of insertion anomalies:• Insert a relation must include the detail of other information

Example: To insert Students data, we need the detail of Prodi• Null is not allowable when inserting a relation

Example: To insert Prodi, we need to insert Student Data first as Student Data is not null

NIM Name Address Prodi Kaprodi

001 Aldo Emerald C1 Serpong TI Jacky

002 Bernard Crystal B1 Serpong SI Wayan

003 Cameron Aqua Marine T1 Serpong TI Jacky

004 Demi Illago R1 Serpong SI Wayan

005 Emma Crystal B2 Serpong SI Wayan

Prodi KaprodiTI JackySI Wayan

Prodi

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Deletion Anomalies

StudentsProdi

• When we delete a tuple of a relation, the other information is also lost.

• Example: When we delete student=003, information about Prodi is also lost.

NIM Name Address Prodi Kaprodi

001 Aldo Emerald C1 Serpong TI Jacky

002 Bernard Crystal B1 Serpong SI Wayan

003 Cameron Aqua Marine T1 Serpong TI Jacky

004 Demi Illago R1 Serpong SI Wayan

005 Emma Crystal B2 Serpong SI Wayan

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Modification Anomalies

StudentsProdi

• When we try to update a value of an attribute, we need to update all tuples at the same attribute. Otherwise, the relation becomes inconsistency

• Example when we need to change the Kaprodi from Wayan to become Made, we need to change all Kaprodi=Wayan

NIM Name Address Prodi Kaprodi

001 Aldo Emerald C1 Serpong TI Jacky

002 Bernard Crystal B1 Serpong SI Wayan

003 Cameron Aqua Marine T1 Serpong TI Jacky

004 Demi Illago R1 Serpong SI Wayan

005 Emma Crystal B2 Serpong SI Wayan

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Functional Dependencies

• Functional Dependency describes the relationship between attributes in relation.

• If A and B are attributes of a relation R, B is functionally dependent on A (denoted AB) if each value of A is associated with exactly one value of B.

• We can say A functionally determines B.

• Functional Dependencies can also include a set of attributes.• If A,B,C, and D are attributes of a relation R, (C,D) is functionally

dependent on (A,B), denoted (A,B)(C,D) if each value of (A,B) is associated with exactly one value of (C,D)

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Determinant and not determinant

• Determinant refers to the attribute, or group of attributes, on the left hand side of the arrow of a functional dependencies. If AB, the A is the Determinant.

• From determinant to another attribute, the relationship must be 1:1 since it must be associated wit exactly one value of that attribute.

• Example we can determine Name, Address, City from its NIM. NIM is the determinant. Relationship from NIM to Name is one to one. NIMName.

• City does not functionally determine NIM as the relationship from City to NIM is one to many (Tangerang has more than one NIMs). City NIM

x

NIM Name Address City

001 Aldo Emerald C1 Serpong Tangerang

002 Bernard Crystal B1 Jakarta

003 Cameron Aqua Marine T1 Serpong Tangerang

004 Demi Illago R1 Serpong Tangerang

005 Emma Crystal B2 Serpong Tangerang

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Type of Functional Dependency

• There are two types of functional dependency, which are full functional dependency and partial dependency.

• Full functional dependency indicates that if A,B, and C are attributes of a relation, C is fully functionally dependent on (A,B) if C functionally dependent on (A,B) but not on A and not on B.

(A,B) C but AC and BC.

• Partial dependency indicates that if A,B, and C are attributes of a relation, C is partial dependent on combination of A and B, denoted (A,B), if C functionally dependent on (A,B) and C also functionally dependent on any A or B.

(A,B) C but AC or BC.

• If A is a single attribute and AC then C full functional dependency on A because we can’t break down A into other attributes.

x x

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Example of Functional Dependencies

NIM Name Address City Prodi Kaprodi

001 Aldo Emerald C1 Serpong Tangerang TI Jacky

002 Bernard Crystal B1 Jakarta SI Wayan

006 Cameron Student Dormitory Tangerang TI Jacky

007 John Student Dormitory Tangerang SI Wayan

008 John Crystal B2 Serpong Tangerang SI Wayan

• Combination of NIM and Name determines the Prodi. Thus, Prodi functionally dependent on (NIM,Name) noted (NIM,Name)Prodi.However, NIM also determines Prodi. Thus, NIMProdi. In conclusion, Prodi has partial dependency on (NIM, Name).

• Prodi has a full functional dependency on combination of Name and Address as Not any of Name or Address determines Prodi but (Name,Address)Prodi.

• Prodi has full functional dependency on NIM.

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Transitive Dependency

• Transitive dependency is a condition where A, B, and C are attributes of a relation R such that AB and BC, then C is transitive dependency on A via B or AC.

NIM Name Address City Prodi Kaprodi

001 Aldo Emerald C1 Serpong Tangerang TI Jacky

002 Bernard Crystal B1 Jakarta SI Wayan

003 Cameron Aqua Marine T1 Serpong Tangerang TI Jacky

004 Demi Illago R1 Serpong Tangerang SI Wayan

005 Emma Crystal B2 Serpong Tangerang SI Wayan

• Example NIMProdi and ProdiKaprodi then NIMKaprodi.

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Identifying Primary Key Using Functional Dependencies

• The main purpose of functional dependencies is to specify a set candidate key.• From those candidate keys, we can identify one primary key.

NIM Name Address City Prodi Kaprodi

001 Aldo Emerald C1 Serpong Tangerang TI Jacky

002 Bernard Crystal B1 Jakarta SI Wayan

003 CameronAqua Marine T1 Serpong Tangerang TI Jacky

004 Demi Illago R1 Serpong Tangerang SI Wayan

005 Emma Crystal B2 Serpong Tangerang SI Wayan

• Four functional dependencies:– NIM Name, Address, City, Prodi and Kaprodi– ProdiKaprodi– KaprodiProdi– (Name, Addres, City)NIM

• All attributes that are not part of primary key if functionally dependent on the key. As all attributes functionally dependent on NIM, then NIM is the primary key.

• NIM is chosen rather than (Name, Addres, City) as it more atomic.• Prodi and Kaprodi are not candidate keys as their relationship to other attributes are 1:*

StudentProdi

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Relationship between the normal forms

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Un-normalized Form (UNF)

• Definition: a table that contains one or more repeating groups.• Repeating group refers to an attribute or a set of attribute in a table which occurs with

multiple values for a single occurrences of nominated key attributes for that table.• Key attribute is attribute(s) that uniquely identify each row within the un-normalized table.

NIM Name Address City Prodi Kaprodi CourseCode CourseName Lecturerid LecturerName001 Aldo Emerald C1 Serpong Tangerang TI Jacky TI403 Database System L001 Aryl TI405 Oracle SQL L002 Mayya TI407 Cisco L003 Tarrie002 Bernard Crystal B1 Jakarta SI Wayan TI403 Database System L001 Aryl SI401 Data Analysist L004 Anank TI407 Cisco L003 Tarrie

003 CameronAqua Marine T1 Serpong Tangerang TI Jacky TI403 Database System L001 Aryl

TI405 Oracle SQL L002 Mayya TI407 Cisco L003 Tarrie004 Demi Illago R1 Serpong Tangerang SI Wayan TI403 Database System L001 Aryl SI401 Data Analysist L004 Anank TI407 Cisco L003 Tarrie005 Emma Crystal B2 Serpong Tangerang SI Wayan TI403 Database System L001 Aryl TI405 Oracle SQL L002 Mayya TI407 Cisco L003 Tarrie

What is the key attribute for above table? What are the repeating groups?

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First Normal Form (1NF)

• Definition: a relation in which intersection of each row and column contains one and only one value.

• Transforming from UNF to 1NF:– Identify and remove repeating groups within a table– There are two common approach in removing repeating groups from

un-normalized table:1. By entering appropriate data in the empty columns of rows

containing the repeating data (Flattening the table).2. By placing the repeating data, along with a copy of original key

attributes in a separate relation.

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Transform from UNF to 1NF

• Flattening the table:

NIM Name Address City Prodi Kaprodi CourseCode CourseName Lecturerid LecturerName

001 Aldo Emerald C1 Serpong Tangerang TI Jacky TI403 Database System L001 Aryl

001 Aldo Emerald C1 Serpong Tangerang TI Jacky TI405 Oracle SQL L002 Mayya

001 Aldo Emerald C1 Serpong Tangerang TI Jacky TI407 Cisco L003 Tarrie

002 Bernard Crystal B1 Jakarta SI Wayan TI403 Database System L001 Aryl

002 Bernard Crystal B1 Jakarta SI Wayan SI401 Data Analysist L004 Anank

002 Bernard Crystal B1 Jakarta SI Wayan TI407 Cisco L003 Tarrie

003 Cameron Aqua Marine T1 Serpong Tangerang TI Jacky TI403 Database System L001 Aryl

003 Cameron Aqua Marine T1 Serpong Tangerang TI Jacky TI405 Oracle SQL L002 Mayya

003 Cameron Aqua Marine T1 Serpong Tangerang TI Jacky TI407 Cisco L003 Tarrie

004 Demi Illago R1 Serpong Tangerang SI Wayan TI403 Database System L001 Aryl

004 Demi Illago R1 Serpong Tangerang SI Wayan SI401 Data Analysist L004 Anank

004 Demi Illago R1 Serpong Tangerang SI Wayan TI407 Cisco L003 Tarrie

005 Emma Crystal B2 Serpong Tangerang SI Wayan TI403 Database System L001 Aryl

005 Emma Crystal B2 Serpong Tangerang TI Jacky TI405 Oracle SQL L002 Mayya

005 Emma Crystal B2 Serpong Tangerang SI Wayan TI407 Cisco L003 Tarrie

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Transform from UNF to 1NF

• Making separate tables along with the key attribute (NIM):

NIM Name Address City Prodi Kaprodi001 Aldo Emerald C1 Serpong Tangerang TI Jacky002 Bernard Crystal B1 Jakarta SI Wayan003 Cameron Aqua Marine T1 Serpong Tangerang TI Jacky004 Demi Illago R1 Serpong Tangerang SI Wayan005 Emma Crystal B2 Serpong Tangerang SI Wayan

NIM CourseCode CourseName Lecturerid LecturerName001 TI403 Database System L001 Aryl001 TI405 Oracle SQL L002 Mayya001 TI407 Cisco L003 Tarrie002 TI403 Database System L001 Aryl002 SI401 Data Analysist L004 Anank002 TI407 Cisco L003 Tarrie003 TI403 Database System L001 Aryl003 TI405 Oracle SQL L002 Mayya003 TI407 Cisco L003 Tarrie004 TI403 Database System L001 Aryl004 SI401 Data Analysist L004 Anank004 TI407 Cisco L003 Tarrie005 TI403 Database System L001 Aryl005 TI405 Oracle SQL L002 Mayya005 TI407 Cisco L003 Tarrie

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Second Normal Form (2NF)

• Definition: A relation that is in the first normal form and every non-primary key attribute is fully functionally dependent on the primary key.

• Transforming 1NF to 2NF:– Identify partial dependent attributes– Remove all partial dependent attributes from the table in a new table

along with copy of their determinant

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Transform from 1NF to 2NF

• Which attribute(s) is the primary key?• Which attributes are partially dependent on the primary key?

NIM Name Address City Prodi Kaprodi

001 Aldo Emerald C1 Serpong Tangerang TI Jacky

002 Bernard Crystal B1 Jakarta SI Wayan

003 Cameron Aqua Marine T1 Serpong Tangerang TI Jacky

004 Demi Illago R1 Serpong Tangerang SI Wayan

005 Emma Crystal B2 Serpong Tangerang SI Wayan

• As NIM is a single attribute, all attributes are fully functional dependent on NIM.

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Transform from 1NF to 2NF

• Which attribute(s) is the primary key?• Which attributes are partially dependent on the primary key?

• (NIM, CourseCode) all attributes (Primary Key)• CourseCode CourseName (Partially Dependent)• Is CourseCodeLecturerId?

NIM CourseCode CourseName Lecturerid LecturerName001 TI403 Database System L001 Aryl001 TI405 Oracle SQL L002 Mayya001 TI407 Cisco L003 Tarrie002 TI403 Database System L001 Aryl002 SI401 Data Analysist L004 Anank002 TI407 Cisco L003 Tarrie003 TI403 Database System L001 Aryl003 TI405 Oracle SQL L002 Mayya003 TI407 Cisco L003 Tarrie004 TI403 Database System L001 Aryl004 SI401 Data Analysist L004 Anank004 TI407 Cisco L003 Tarrie005 TI403 Database System L001 Aryl005 TI405 Oracle SQL L002 Mayya005 TI407 Cisco L003 Tarrie

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Transform from 1NF to 2NF

CourseCode CourseNameSI401 Data AnalysistTI403 Database SystemTI405 Oracle SQLTI407 Cisco

NIM CourseCode Lecturerid LecturerName001 TI403 L001 Aryl001 TI405 L002 Mayya001 TI407 L003 Tarrie002 SI401 L004 Anank002 TI403 L001 Aryl002 TI407 L003 Tarrie003 TI403 L001 Aryl003 TI405 L002 Mayya003 TI407 L003 Tarrie004 SI401 L004 Anank004 TI403 L001 Aryl004 TI407 L003 Tarrie005 TI403 L001 Aryl005 TI405 L002 Mayya005 TI407 L003 Tarrie

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Third Normal Form (3NF)

• Definition: A relation that is in first and second normal form and in which no non-primary-key attribute is transitive dependent on the primary key

• Transforming from 2NF to 3NF:– Remove all transitive dependencies by placing attributes in new table

along with a copy of the determinant.

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Transforming 2NF to 3NF

• NIMProdi but ProdiKaprodi (Transitive Dependency)

NIM Name Address City Prodi Kaprodi

001 Aldo Emerald C1 Serpong Tangerang TI Jacky

002 Bernard Crystal B1 Jakarta SI Wayan

003 Cameron Aqua Marine T1 Serpong Tangerang TI Jacky

004 Demi Illago R1 Serpong Tangerang SI Wayan

005 Emma Crystal B2 Serpong Tangerang SI Wayan

NIM Name Address City Prodi001 Aldo Emerald C1 Serpong Tangerang TI002 Bernard Crystal B1 Jakarta SI003 Cameron Aqua Marine T1 Serpong Tangerang TI004 Demi Illago R1 Serpong Tangerang SI005 Emma Crystal B2 Serpong Tangerang SI

Prodi KaprodiSI WayanTI Jacky

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Transform from 2NF to 3NF

CourseCode CourseNameSI401 Data AnalysistTI403 Database SystemTI405 Oracle SQLTI407 Cisco

NIM CourseCode Lecturerid LecturerName001 TI403 L001 Aryl001 TI405 L002 Mayya001 TI407 L003 Tarrie002 SI401 L004 Anank002 TI403 L001 Aryl002 TI407 L003 Tarrie003 TI403 L001 Aryl003 TI405 L002 Mayya003 TI407 L003 Tarrie004 SI401 L004 Anank004 TI403 L001 Aryl004 TI407 L003 Tarrie005 TI403 L001 Aryl005 TI405 L002 Mayya005 TI407 L003 Tarrie

• (NIM,CourseCode)LecturerId, but LecturerIdLecturerName (Transitive Dependency)

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Transform from 2NF to 3NF

CourseCode CourseNameSI401 Data AnalysistTI403 Database SystemTI405 Oracle SQLTI407 Cisco

Lecturerid LecturerNameL001 ArylL002 MayyaL003 TarrieL004 Anank

NIM CourseCode Lecturerid001 TI403 L001001 TI405 L002001 TI407 L003002 SI401 L004002 TI403 L001002 TI407 L003003 TI403 L001003 TI405 L002003 TI407 L003004 SI401 L004004 TI403 L001004 TI407 L003005 TI403 L001005 TI405 L002005 TI407 L003

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Result from UNF to 3NF

CourseCode CourseNameSI401 Data AnalysistTI403 Database SystemTI405 Oracle SQLTI407 Cisco

Lecturerid LecturerNameL001 ArylL002 MayyaL003 TarrieL004 Anank

NIM CourseCode Lecturerid001 TI403 L001001 TI405 L002001 TI407 L003002 SI401 L004002 TI403 L001002 TI407 L003003 TI403 L001003 TI405 L002003 TI407 L003004 SI401 L004004 TI403 L001004 TI407 L003005 TI403 L001005 TI405 L002005 TI407 L003

NIM Name Address City Prodi001 Aldo Emerald C1 Serpong Tangerang TI002 Bernard Crystal B1 Jakarta SI003 Cameron Aqua Marine T1 Serpong Tangerang TI004 Demi Illago R1 Serpong Tangerang SI005 Emma Crystal B2 Serpong Tangerang SI

Prodi KaprodiSI WayanTI Jacky