Tag: technology

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Questions Related to technology

Multiple choice technology databases

You created a view called EMP_DEPT_VU that contains three columns from the EMPLOYEES and DEPARTMENTS tables: EMPLOYEE_ID, EMPLOYEE_NAME AND DEPARTMENT_NAME. The DEPARTMENT_ID column of the EMPLOYEES table is the foreign key to the primary key DEPARTMENT_ID column of the DEPARTMENTS table. You want to modify the view by adding a fourth column, MANAGER_ID of NUMBER data type from the EMPLOYEES tables. How can you accomplish this task?

  1. ALTER VIEW emp_dept_vu (ADD manager_id NUMBER);

  2. MODIFY VIEW emp_dept_vu (ADD manager_id NUMBER);

  3. ALTER VIEW emp_dept_vu AS SELECT employee_id, employee_name, department_name, manager_id FROM employee e, departments d WHERE e.department_id = d.department_id;

  4. CREATE OR REPLACE VIEW emp_dept_vu AS SELECT employee_id, employee_name, department_name, manager_id FROM employees e, departments d WHERE e.department_id = d.department_id;
Reveal answer Fill a bubble to check yourself
D Correct answer
Full explanation
Multiple choice technology databases

Bit map Vs B-tree indexes
    1. Bit map indexes are used on low-cardinality columns(having low distinct values) 2.B-tree indexes are most effective for high-cardinality data(only for unique columns)

  2. B-tree indexes cannot be used in environments typically have large amounts of data and ad hoc queries

  3. bitmap indexes can be created on partitioned tables

  4. All of the above
Reveal answer Fill a bubble to check yourself
D Correct answer