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The External or View Level
The external or view level is the highest level of abstraction of database. It gives a window on the conceptual view, which permits the user to see only the data of interest to them. The user can be either an end user or an application program. There can be a lot of external views as any number of external schemas can be defined and they can overlap each other. It contains of the definition of logical records and relationships in the external view. It also has the methods for deriving the objects such as attributes, entities and relationships in the external view from the Conceptual view.
Logical DBMS Architecture
Write short note on Events Events consist of inputs, interrupts, decisions and actions performed by any external device or users. Every event always has a sender and receiver.
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Discuss the types of integrity constraints in which must be checked for the update operations - Insert and Delete. Give examples. Insert operation can violet any of the subse
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