With reference to the database schema of the COMPANY database discussed in the class having the relations: Employee, Department, Dept$\_$Locations, Project, Works$\_$on and Dependent. Consider one possible state of the COMPANY relational database schema.

State which Integrity constraint will be violated if the following operations are applied. Also discuss the ways of enforcing the constraints.

a$)$ Insert $<mi\; id="EditorElement\_17724341"></mi>$Preeti$,$G$,$Naidu$,903599999,1990-04-05,102$ Secunderabad, Telangana$,$ F$,270000,$ NULL, $5>$ into EMPLOYEE

b$)$ Delete the EMPLOYEE tuple with Ssn $=123456789.$

c$)$ Insert NULL, $49\mathrm{.}0>$ into WORKS$\_$ON

d$)$ Modify the Hours attribute of the WORKS$\_$ON tuple with Essn $=999887777$ and Pno $=10$ to $25\mathrm{.}0.$

provide all steps