T2
- 1. Part A: Answer1. Specializationhierarchiesenable the datamodel tocapture additional semanticcontent(meaning) intothe ERD. Specializationisatop-downapproachinwhicha higher-level entityisdividedinto multiple specializedlower-level entities. A specializationhierarchyprovidesthe meansto: Supportattribute inheritance. Define aspecial supertypeattribute knownasthe subtype discriminator. Define disjoint/overlappingconstraintsandcomplete/partial constraints. Answer2. Specializationandgeneralizationare fundamental conceptsindatabase modelingthatare useful for establishingsuperclass-subclassrelationships. Specializationisa top-downapproachinwhicha higher-level entityisdividedinto multiple specialized lower-levelentities.Inadditiontosharingthe attributesof the higher-level entity,these lower-level entitieshave specificattributesof theirown.Specializationisusuallyused to findsubsetsof anentitythathas a few differentoradditionalattributes. The followingenhancedentityrelationshipdiagramexpressesthe entitiesinahierarchical database to demonstrate specialization: Generalizationisabottom-upapproachinwhichmultiple lower-level entitiesare combinedtoform a single higher-level entity.Generalizationisusuallyusedtofindcommonattributesamongentities to forma generalizedentity.Itcanalsobe thoughtof as the opposite of specialization. The followingenhancedentityrelationshipdiagramexpressesentitiesinahierarchical database to demonstrate generalization: Answer3. Two criteriahelpthe designerdeterminewhentouse subtypesandsupertypes: There mustbe different,identifiable kindsortypesof the entityinthe user’senvironment. The differentkindsortypesof instancesshouldeachhave one ormore attributesthatare unique tothat kind or type of instance. Answer4. No change overtime:If an attribute hassemanticmeaning,itmightbe subjecttoupdates.Thisis whynamesdo notmake good primarykeys.If youhave Vickie Smithasthe primarykey,what happensif she changeshername whenshe getsmarried?If a primarykeyissubjectto change,the foreignkeyvaluesmustbe updated,thusaddingtothe database workload.Furthermore,changing a primarykeyvalue meansthatyou are basicallychangingthe identityof anentity.Inshort,the PK shouldbe permanentandunchangeable.
- 2. Answer5. Composite primarykeysare particularlyusefulintwocases: As identifiersof composite entities,whereeachprimarykey combinationisallowedonly once in the M:N relationship. As identifiersof weakentities,wherethe weakentityhasastrongidentifyingrelationship withthe parententity. Part B: Answer1. TinyCollege.accdb Part C: No. Criteria Activity 1 Attendance at weekly meetings Information exchanged through telephone and social media, for example, WhatsApp group used to exchange any type of notes, working notes from tutorial classes, other type of documents, and pictures for the assigned tasks and arranged Zoom meetings for discussions. 2 Weekly activity log Workload divided by the leader after discussing with other group members and started planning to complete the tasks effectively on time. Discussion made to organise the activities in an appropriate manner to complete the tasks within specified deadlines. 3 Time management We did 40 minutes discussion on Zoom for the division of work among all the group members and also decided to arrange daily meetings for 15 minutes after the tutorial class through WhatsApp Group or Zoom to keep the things on track.
- 3. 4 Tasks To fulfil the requirements of User View 4 To Develop the structure of database by drawing an entity-relationship (E-R) diagram and EERD for the enterprise. To Create Forms in Microsoft Access to populate data in the tables as per the requirement. Report Writing 5 Actual contribution to group project I have been assigned 4 tasks and started working on them to meet the requirements and deadlines as well.