Suppose that you decide to convert Is A hierarchies into the relational model by adding a new attribute (such as Status in the case of Student entities, the second option for representing Is A hierarchies). What kind of problems exist if subentities are not disjoint (e.g., if a secretary can also be a technician)? What problems exist if the covering constraint does not hold (e.g., if some employees are not classi?ed as either secretary or technician)?
What will be an ideal response?
If sub-entities are not disjoint then some tuples would be duplicated (except for the value of the new attribute that simulates the hierarchy). If the covering constraint does not hold, then we would have to use NULs to represent the tuples that do not belong
to any one of the subentities.
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Case PPT 8-1Shannon is preparing a presentation for a trade show. Her company will have a booth, and she wants to create a presentation that can play continuously. Shannon wants to use the slides in the presentation to create a second slide show that is slightly different by changing the order and not using all of the slides. Which command can she use to do this?
A. Rehearse Timings B. Custom Slide Show C. Start Recording from Current Slide D. Broadcast Slide Show
If the circuit files are lost or destroyed, what document are Technical Control Facilities required to obtain?
a. The latest telecommunications service order (TSO) that reflects the current end-to-end circuit configuration. b. The original TSO and the original circuit test data. c. The latest TSO and the latest circuit test data. d. The original TSO that established the circuit.
The purpose of a ______________ is to provide a mechanism for recovering files encrypted with EFS if there's a problem with the user's original private key.?
Fill in the blank(s) with the appropriate word(s).
An organization that provides a wide range of support services to users is called a(n) ____.
A. user support center B. help desk C. peer support D. hotline