Explain why the REFERENCES privilege is necessary. Give an example of how it is possible to obtain partial information about the contents of a relation by creating foreign-key constraints referencing that relation.
What will be an ideal response?
Suppose Phone number is a candidate key in the Loan relation. One can then ?nd out who has loans by creating a relation, Probe, with the attribute Phone, which REFERENCES the Phone attribute in Loan. Then, by exhaustively inserting all possible phone numbers and recording which ones produce errors, such a user would ?nd out the phone numbers of all people who have loans. Reverse telephone lookup using a number of services on the Web will make it possible to also ?nd names and addresses of those people.
You might also like to view...
What are the leaves of a tree?
What will be an ideal response?
The database schema is defined by the DDL components in the SQL programming language.
Answer the following statement true (T) or false (F)
One way to shorten the critical path is to add__________________ hours, which are work hours outside of those specified by the calendar, to resources assigned to critical tasks.
Fill in the blank(s) with the appropriate word(s).
Which of the following is NOT a level of advice regarding performance as analyzed by the Performance Analyzer?
A. Issue B. Recommendation C. Suggestion D. Idea