The tutor claim system is an online system whereby casual tutors can claim their work

for payment. This payment claim is done fortnightly. Casual tutors are teaching

assistants who are hired for each subject in each semester. All of them are students,

mostly postgraduate students. These tutors are hired by the department to assist the

lecturers in delivering the subject. This assistance typically includes tutorial and lab

support, consultation, and marking $($exams and assignments$).$ Prior to the online system,

tutors have to lodge a claim form every fortnight to be approved by the associated lecturer

in order to be processed in the financial system. With this online system, payment claims

can be made through the web. Each lecturer typically has a specific budget, which can be

used to hire casual tutors for the semester. Each lecturer still needs to approve$/$reject

claims made by their tutors. Once a claim is approved, the budget is appropriately reduced,

so that the lecturer knows how much budget he$/$she still has budget he$/$she still has.

a$)$ Provide TWO transaction scenarios with reference to the ERD $($see Figure $1),$ where concurrency control is necessary. You can create the following serial execution table for explanation.

b$)$ Write MySQL statements to perform locking to update a data value in the TUTOR table.

c$)$By using the pessimistic locking method, suppose there are two transaction requests to a MYSQL DBMS$.$ The first transaction inserts a new claim into the system for TutorID $0582.$ While the second transaction requests to read for the same Tutor$\_$ID$$s claim. That is followed by updating claim status to $$In progress$.$ Illustrates the locking procedure by using a transaction table $($see below$).$ You can choose the binary or two$-$phase locking method for illustrating.