DBMS-QUIZ

In a DBMS, which command is used to set a point in the transaction to which you can roll back later?

• COMMIT

• ROLLBACK

• SAVEPOINT

• SET TRANSACTION

Which of the following is true about the COMMIT command in DBMS?

• It sets the isolation level of the current transaction.

• It permanently saves the changes made in the current transaction.

• It allows you to undo all changes made in the transaction.

• It creates a savepoint that can be used for rollback.

What is the main advantage of using PL/SQL in Oracle DBMS?

• It allows procedural logic, which makes SQL queries more efficient.

• It is used only for basic data retrieval.

• It provides support for object-oriented programming.

• It enables execution of SQL queries only in the client-side application.

Which of the following is NOT a valid component of a PL/SQL block?

• • Declaration

• • Execution

• • Commit

• • Exception Handling

Which of the following is the primary purpose of using triggers in a database?

• To optimize query performance by automatically indexing tables whenever data is modified.

• To automatically maintain data integrity by synchronizing changes between related tables.

• To adjust table structures dynamically when data modifications occur.

• To enforce business rules by triggering automatic actions in response to data changes.

What is the problem with this trigger?

• • The trigger will not work because :NEW.emp_name is not valid in a BEFORE INSERT trigger.

• • The trigger is valid and will work as intended.

• • RAISE_APPLICATION_ERROR can only be used in a BEFORE UPDATE trigger.

• • The trigger will only work if the column emp_name is explicitly defined as NOT NULL.

Which of the following is true for the following trigger?

• • The trigger is valid and will execute after every update on the salary field.

• • The trigger will fail because :NEW.salary cannot be used in an AFTER UPDATE trigger.

• • The trigger will only execute if the salary value is greater than 100000.

• • The trigger will cause an error if the salary value is less than 100000.

Which of the following defines a strict schedule?

• A schedule where a transaction commits before accessing any shared data item.

• A schedule in which all conflicting transactions are executed serially.

• A schedule where all transactions must be committed before any other transaction can access data.

• A schedule in which no transaction can read or write any data item that another uncommitted transaction is accessing.

A schedule is __________ if it is conflict equivalent to a serial schedule.

• Conflict serializable

• Conflicting

• Conflict serial schedule

• None of these

State true or false: If I = read(Q) and J = read(Q) then the order of I and J does not matter.

(a)