Computer Science

Running head : COMPUTER SCIENCE Part 1 emblem SEQ Figure \ Arabic 1 : ERD(bFigure SEQ Figure \ ARABIC 2 : alto fetchheriance schemaThe above figure is described as followsIn the client panel , cust_no is the indigenous place and request_num is the unknown attainIn the force req lengthen , request_num is the primary feather winding paint , F matter and cust_no and EP subject be the contradictory keysIn the facility mesa , Fnumber is the primary key and resource is the foreign keyIn the employee circuit board , number is the primary keyIn the event plan lines tabular array , resource is the primary key , number and EPnumberIn the location table , number is the primary key and resource is the foreign keyIn the event plan table , EPnumber is the primary key and request_num resource and number ar the foreign keys(c . Ye s the tables are in BCNF . In each(prenominal) the tables above the relations are built in much(prenominal) a fashion that super key of the relations power eithery determines all the attri moreoveres in the apt(p) relationsThere is no instance where there is a key which would functionally determine a non-prime attributePart Two2 (aSELECT s .identifier , s .name , s .email , s .major , f .nameFROM Student s , Faculty fWHERE s .facid f .facid(bSELECT c .compid , c .name ,.NumOpeningsFROM fraternity c , positionp WHERE c .compid.compid AND.NumOpenings coulomb(cSELECT s .identifier , s .nameFROM Student s , Interviewer I , telephoner c , Interview int InterviewConduct icWHERE s .stdid int .stdid ANDint .interviewid ic .interviewid ANDic .interviewerid i .interviewerid ANDi .compid c .compid ANDc .compname similar `NTU Corporation(dSELECT s .identifier , s .nameFROM Student s , Interviewer I , Company c , Interview int InterviewConduct ic . Positionp WHERE s .stdid int .stdid A NDint .interviewid ic .interviewid ANDic .in! terviewerid i .interviewerid ANDi .compid c .compid ANDp .compid c .compid ANDc .compname resembling `NTU Corporation ANDp .desc LIKE ` programming job4Outer Join operation is useful in cases where the introduction of a weak entity type exists in the database schema . inclined the pursuit relation the out bring together relations beat to its dependable swingEmployeeEmp_id name Dept_id Phone1 Partha 1 99999992 Harry 1 90898983 flaxen 2 89645654 Monica 1 78787895 Tom 3 8989898 DepartmentDept_id name1 Finance2 Admin3 HR4 ITIf we happen to join the two tables to find how many employees work for the incisions , the IT department would non be shown as there is no mention to that in the employee table .

Say IT department has been introduced newly in the company , but without the outer join the IT dept would not appear at all giving an impression that it does not existThe following is the path to furbish up the full outer join in Oracle and Microsoft main course DatabaseSELECT d .name , count (e .emp_idFROM department d full outer join employee e ON d .dept_id e .dept_idGROUP BY e .emp_id(bThe season number statement initializes the customer id to yard increments the valuate by 100 . The trigger created gets fired at the onset of inserting a speech on the customer table . The SQL query transforms the customer_id field with the sequence created . The dual table holds the value of the sequence created , it contains the incremented valueThe oracle functions and triggers do almost the same function however the point of remainder is that in triggers there is no return value whereas functions bring on a return value(cThe relations log would entail the following in the event of body failureIf there is a outline ! failure at 8 :43 the following would result placeThe transaction log would pock the immediate last find outpoint to check the statusChecking would imply which are the legal proceeding the system requires to use and which ones to rollbackOnce it finds that transactions 5 ,6 and 7 are label to be roll backed it automatically does itThe other transactions labeled other than the mentioned ones are not taken care at allThese form some of the most requirement transactions which postulate to be roll backed in an event of failureReferences / BibliographyNavathe Elmasri (2004 . fundamental principle of Database systems , Singapore Pearson Education PAGE 9 ...If you want to get a full essay, order it on our website: OrderEssay.net

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