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SQL Test Review - 3 important concepts
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- 13 Uses of Views1. Views contribute to the data independence. A view is a virtual table, and when there is a change in the way data is accessed , or stored, the view adjusts its values and it allows the user to the access data in the same way.
2. Views also provide security by only allowing certain users to see certain information through views. Ex: MIS Teachers can only see MIS Students or MIS Courses.
3.Views also provide an efficient way access certain data, without having to re-write queries. - 2Problem with NullsThe problem with nulls is that since they are valueless, they are left out from evaluation from queries. Example: You want the non-MIS Majors, but you an an undecided student with a 'null'. The system will not send the undecided student, since it is "empty" or "without value".
- 3Data IndependenceImmunity of applications to changes in storage, structure, and/or access strategy.
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- (Reviews) Database Systems Fichas sobre SQL Test Review - 3 important concepts, creado por SERGIO GUTIERREZ el 11/10/2017.
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- SERGIO GUTIERREZ
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