Tag: databases

Quizzes (243) Questions (4862)

Questions Related to databases

Multiple choice technology databases

Merge Syntax

  1. A. MERGE INTO <<target_table_name>> USING <<source_table_name>> WHEN MATCHED THEN UPDATE ------ WHEN NOT MATCHED THEN INSERT -------

  2. B. MERGE <<target_table_name>> USING <<source_table_name>> WHEN MATCHED THEN UPDATE ------ WHEN NOT MATCHED THEN INSERT -------

  3. C. MERGE INTO <<target_table_name>> USING <<source_table_name>> WHEN EXISTS THEN UPDATE ------

  4. D. MERGE INTO <<target_table_name>> USING <<source_table_name>> WHEN NOT MATCHED THEN INSERT ------

  5. Both A and D
Reveal answer Fill a bubble to check yourself
A Correct answer
Full explanation
Multiple choice technology databases

Which two statements about sequences are true?

  1. A. You use a NEXTVAL pseudo column to look at the next possible value that would be generated from a sequence, without actually retrieving the value

  2. B. You use a CURRVAL pseudo column to look at the current value just Generated from a sequence, without affecting the further values to be generated from the sequence.

  3. You use a NEXTVAL pseudo column to obtain the next possible value from a sequence by actually retrieving the value from the sequence

  4. Both A and B
Reveal answer Fill a bubble to check yourself
D Correct answer
Full explanation
Multiple choice technology databases

You need to perform certain data manipulation operations through a view called EMP_DEPT_VU, which you previously created. You want to look at the definition of the view (the SELECT statement on which the view was create.) How do you obtain the definition of the view?

  1. Use the DESCRIBE command in the EMP_DEPT VU view.

  2. Use the DEFINE VIEW command on the EMP_DEPT VU view

  3. Use the DESCRIBE VIEW command on the EMP_DEPT VU view

  4. Query the USER_VIEWS data dictionary view to search for the EMP_DEPT_VU view
Reveal answer Fill a bubble to check yourself
D Correct answer
Full explanation
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