RelationalDBDesignRelationalDBDesign


PL/SQL   «Prev  Next»

Querying Object Tables - Quiz

Each question is worth one point. Select the best answer for each question.

 
1. What is the correlation argument for the DEREF operator?
Please select the best answer.
  A. Like VALUE and REF, DEREF expects a table name alias as its correlation argument.
  B. The correlation argument is the object name.
  C. The correlation argument is the object type.
  D. The correlation argument is the REF (reference) to the object.

2. What is the difference between REF and DEREF operators?
Please select the best answer.
  A. REF returns a reference to the object and DEREF returns the object itself.
  B. REF returns the object and DEREF returns the REF of the object after dereferencing it.
  C. There is no difference.
  D. REF returns the value of the object and DEREF returns the object itself.

3. To view the data of the object that is referenced within another object, which operator--REF, DEREF, or VALUE--should you use in a query?
Please select the best answer.
  A. Use the REF operator because it returns the reference to the object within an object table.
  B. Use the DEREF operator because the reference must be dereferenced before displaying the data of the referenced object.
  C. Use the VALUE operator because it returns the complete object.
  D. use a combination of the REF and DEREF operators to return the data from the referenced object.

Score =
Correct answers: