Rearrange the structure of the Class element in Figure 15.4 so that it becomes possible to de?ne the following referential integrity: every student Id mentioned in a Class element references a student from the same document.
What will be an ideal response?
One way to rearrange this element is to represent each student Id in the class using an attribute:
CS308 F1997
If we were to use DTDs, then we could declare:
and ensure that the attribute Id here refers to an existing value in the same document. Unfortunately, there is no way for a DTD to say that this value must be a student Id. In XML schema we can use the key ref element to enforce such a constraint:
where adm is the namespace pre?x used for the document in Figure 15.4 and StudentKey is the primary key de?ned for Student elements:
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In what ways do processors support operating system services?
accessing privileged instructions. b) Most processors provide mechanisms for memory protection and memory management. c) Processors inform the operating system of events such as program execution errors and changes in device status d) all of the above
The current method executing is always the method whose activation record is ________.
a. at the bottom of the stack. b. at the top of the stack. c. never placed on the stack. d. second from the top of the stack, just below the previous method call.
If you have two tables that share a one-to-many relationship, then you can include the table on the many side of the relationship as a(n) ________
Fill in the blank(s) with correct word
The ____ command on the Adjustments submenu produces a grayscale image but leaves the image in the same color mode, usually rendering a flat, uninspiring version.
a. Black and White b. Grayscale c. Desaturate d. Colorless