Question

2) The SQL statement: DROP TABLE STAFF; a) Permanently removes the entire staff table b) Performs a rollback action to refresh the contents of the staff table to the last database commit c) Removes all rows from the table but maintains the table structure d) None of the above 3) Concurrency problems that can occur in a multi-user environment include: a) Conceptual updates b) Isolation updates c) lost updates d) None of the above Questions 4-7 relate to the following relation, R: EE XX Z AA BB CC DD FOLLÎ Î Y FB! 4) Functional Dependency 1 (FDI) can be written as: a) (CC,DD.EE)->(AA,BB) b) (AA)->(CC,DD,EE) c) (AA,BB)->(CC,DD,EE) d) None of the above 5) Functional Dependency 2(FD2) illustrates a: a) Transitive Dependency h) Tullar functional donandan

Answer 1

(2)

Answer: (a) Permanently removes the entire table staff.

Explanation:

DROP statement is used to remove the object completely from database. It deletes all the rows of the table and basic structure of table is also removed from database. It is not possible revert back the table once it is dropped. Once the table is dropped all the references to that table become invalid.

(3)

Answer: (c) Lost updates

Explanation:

When multiple users reads the same data and performs some operation and if the update of one transaction is overwritten by update of another transaction without reading it results in the first update to become lost (write-write conflict).

(4)

Answer: (c) (AA,BB) -> (CC, DD, EE)

Explanation:

Arrows are pointed to CC, DD EE which are coming from AA and BB together. So, CC,DD,EE are functionally dependent on AA and BB. So, both (AA,BB) together derives CC,DD,EE. Therefore, FD1 can be written as (AA,BB) -> (CC, DD, EE).