A empwx s pnameproductx project j pnumberpno workson

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(a) EMP_W_X <-- ( s PNAME='ProductX' (PROJECT)) J (PNUMBER),(PNO) (WORKS_ON) EMP_WORK_10 <-- (EMPLOYEE) J (SSN),(ESSN) ( s HOURS>10 (EMP_W_X)) RESULT <-- P LNAME,FNAME ( s DNO=5 (EMP_WORK_10)) Result: LNAME FNAME Smith John English Joyce (b) E <-- (EMPLOYEE) J (SSN,FNAME),(ESSN,DEPENDENT_NAME) (DEPENDENT) R <-- P LNAME,FNAME (E) Result (empty): LNAME FNAME (c) WONG_SSN <-- P SSN ( s FNAME='Franklin' AND LNAME='Wong' (EMPLOYEE))
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WONG_EMPS <-- (EMPLOYEE) J (SUPERSSN),(SSN) (WONG_SSN) RESULT <-- P LNAME,FNAME (WONG_EMPS) Result: LNAME FNAME Smith John Narayan Ramesh English Joyce (d) PROJ_HOURS(PNO,TOT_HRS) <-- PNO f SUM HOURS (WORKS_ON) RESULT <-- P PNAME,TOT_HRS ( (PROJ_HOURS) J (PNO),(PNUMBER) (PROJECT) ) Result: PNAME TOT_HRS ProductX 52.5 ProductY 37.5 ProductZ 50.0 Computerization 55.0 Reorganization 25.0 Newbenefits 55.0 (e) PROJ_EMPS(PNO,SSN) <-- P PNO,ESSN (WORKS_ON) ALL_PROJS(PNO) <-- P PNUMBER (PROJECT) EMPS_ALL_PROJS <-- PROJ_EMPS -:- ALLPROJS (* DIVISION operation *) RESULT <-- P LNAME,FNAME (EMPLOYEE * EMP_ALL_PROJS) Result (empty): LNAME FNAME (f) ALL_EMPS <-- P SSN (EMPLOYEE) WORKING_EMPS(SSN) <-- P ESSN (WORKS_ON) NON_WORKING_EMPS <-- ALL_EMPS - WORKING_EMPS (* DIFFERENCE *) RESULT <-- P LNAME,FNAME (EMPLOYEE * NON_WORKING_EMPS) Result (empty): LNAME FNAME (g) DEPT_AVG_SALS(DNUMBER,AVG_SAL) <-- DNO f AVG SALARY (EMPLOYEE) RESULT <-- P DNUMBER,AVG_SAL ( DEPT_AVG_SALS * DEPARTMENT ) Result: DNUMBER AVG_SAL Research 33250 Administration 31000 Headquarters 55000 (h) RESULT(AVG_F_SAL) <-- f AVG SALARY ( s SEX='F' (EMPLOYEE) )
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Result: AVG_F_SAL 31000 (i) E_P_HOU(SSN) <-- P ESSN (WORKS_ON J(PNO),(PNUMBER) ( s PLOCATION='Houston' (PROJECT))) D_NO_HOU <-- P DNUMBER (DEPARTMENT) - P DNUMBER ( s DLOCATION='Houston' (DEPARTMENT)) E_D_NO_HOU <-- P SSN (EMPLOYEE J(PNO),(DNUMBER) (D_NO_HOU)) RESULT_EMPS <-- E_P_HOU - E_D_NO_HOU (* this is set DIFFERENCE *) RESULT <-- P LNAME,FNAME,ADDRESS (EMPLOYEE * RESULT_EMPS) Result: LNAME FNAME ADDRESS Wallace Jennifer 291 Berry, Bellaire, TX (j) DEPT_MANAGERS(SSN)<-- P MGRSSN (DEPARTMENT) EMPS_WITH_DEPENDENTS(SSN) <-- P ESSN (DEPENDENT) RESULT_EMPS <-- DEPT_MANAGERS - EMPS_WITH_DEPENDENTS RESULT <-- P LNAME,FNAME (EMPLOYEE * RESULT_EMPS) Result: LNAME FNAME Borg James 6.18 Consider the LIBRARY relational schema shown in Figure 7.20, which is used to keep track of books, borrowers, and book loans. Referential integrity constraints are shown as directed arcs in Figure 7.20, as in the notation of Figure 7.7. Write down relational expressions for the following queries on the LIBRARY database: (a) How many copies of the book titled The Lost Tribe are owned by the library branch whose name is "Sharpstown"? (b) How many copies of the book titled The Lost Tribe are owned by each library branch? (c) Retrieve the names of all borrowers who do not have any books checked out. (d) For each book that is loaned out from the "Sharpstown" branch and whose DueDate is today, retrieve the book title, the borrower's name, and the borrower's address. (e) For each library branch, retrieve the branch name and the total number of books loaned out from that branch.
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