Student. 13 December, 2016. database assignment. Studen

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Student 13 December, 2016 DATABASE ASSIGNMENT
Week 11.Can we have different conceptual schema design for the same application?Answer: no we cannot have different conceptual schema design for the sameapplication because conceptual models the relationships between entitiesused in application. No matter what, the relationships remain same. Whereaswe can use these relations differently on an external end. 2.How database design process differs from a system design process?Answer: database design refers to the process of designing and defining thedatabase tables and attributes. This process requires both physical and logicaldatabase design. It includes data dictionary, records, relationships etc. whereassystem design refers to designing the overall system which includes interfacedesign, architecture definition, modules, data etc. hence database design dealsonly with database development whereas system design deals with defining anddesigning all the parts of the system.3.What are the lessons learned when you created your first ER-diagram?Answer: the lessons learnt are:a.Each entity should have a primary key.b.Relationships should be developed between entities using foreign keys.c.All the entities to be designed should be as per the requirementd.Entities should be atomic.e.The diagram should be in 3NF.f.The multiplicity should be applied to all the relationships.g.Each entity should have a unique name.h.There should not be any redundant in the ERD.i.All the attributes should be dependent on primary key.4.Is ER-Model helpful in providing all the required information about theapplication for which this conceptual schema has been designed?Answer: the ER model provides the information about all the entities andattributes that will be designed into a database for the application. Theconceptual design models the relationships not all the requirements of theapplication. For example modules, interfaces, access rights etc. will not bemodelled in the conceptual model. Hence ER-model only represents thedatabase requirements which are in turned into a physical database and not allother external and internal requirements. 1 | Page

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