Entity Relationship Diagram (ERD) - Assignment
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Added on 2021-02-20
Entity Relationship Diagram (ERD) - Assignment
Added on 2021-02-20
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NORMALISATION
ContentsINTRODUCTION...........................................................................................................................1MAIN BODY...................................................................................................................................1Normalisation and dependency....................................................................................................1a). Dependency diagram..............................................................................................................1b) Identify multivalued dependencies..........................................................................................2c) create dependency graph to set table structure........................................................................3ER diagram..................................................................................................................................5CONCLUSION................................................................................................................................7REFERENCES................................................................................................................................8
INTRODUCTIONNormalisation can be defined as a formal process that helps in assigning all the presentattributes to all the present entities. In this assignment dependency diagram, multivalueddependency and crow's foot ER diagram will be explained in detail.MAIN BODYNormalisation and dependencyNormalisation is a process of organising data into database. It also helps in controllingdata redundancies from relations or set of relations (Chitti, Murkin and Chitchyan, 2019). It alsohelps in eliminating undesirable data anomalies where data upgrading, insertion, deletion candestroy the overall integrity of the data.There are four main types of normalisation form: 1NF, 2NF, 3NF and BCNF. If relation consistof atomic value then it is in 1NF. If relation is in 1NF and all the non key attributes are fullyfunctional and dependent on primary key, then the relation is in 2NF. If the current relation isalready in 2NF and there is no transition dependency that exist then the relation is in 3NF.a). Dependency diagramFirst Normal Form (1NF)emp_idemp_firstnameemp_lastnameEmp_phonenoEmp_addEmp_ageP_idEmployee tableSecond Normal Form (2NF)emp_idemp_firstnameemp_lastnameEmp_phonenoEmp_addEmp_ageP_idEmployee tableP_idP_nameP_rankP_typeP_phonenoP_addressProfessor table1
emp_idP_idP_rankAssign tableThird Normal Form(3NF)E_idP_rank P_typeP_idP_idP_nameP_rankb) Identify multivalued dependenciesIt can be defined as a constraint which helps in setting relation between two set ofattributes. Or in other words it helps in showing dependency of two or more than two variableson third variable.For example in the below diagram professor name and professor rank are dependent uponprofessor id.P_idP_nameP_rank111Gheeprofessor112RankinAsst. Professor113OrtegaAssociate professor114SmithAssociate professor2
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