Suppose the following operations is applied directly to the database state shown in figure above Discuss all integrity constraints violated by each operation, if any.

Operation: $1)$ Delete the WORKS$\_$ON tuples with Essn $=\text{'}333445555\text{'},2)$ Modify the Hours attribute of the WORKS$\_$ON tuple with Essn $=\text{'}999887777\text{'}$ and Pno $=10$ to NULL

Also, Discuss all integrity constraints violated by each operation, if any.