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The Conceptual Level or Global level
The conceptual level presents a logical view of the complete database as a unified whole. It permits the user to bring all the data in the database mutually and see it in a constant manner. However, there is only one conceptual schema per database. The primary stage in the design of a database is to describe the conceptual view, and a DBMS gives a data definition language for this purpose. It tells all the records and relationships included in the database.
The data definition language used to make the conceptual level must not specify any physical storage considerations that should be handled by the physical level. It does not give any storage or access details, but tells the information content only.
Object-oriented decompositions Object-oriented decompositions of systems better are able to cope with change. Each subsystem has a well-defined interface which communicates with
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Define blocks? The database system resides eternally on non-volatile storage, and is into fixed-length storage units known as blocks.
BCNF Boyce-Codd Normal Form A relation schema R is in BCNF if it is in 3NF and accepts an additional constraint that for every FD X A, X has to be a candidate key. If a relati
2NF Normal Form : A relation schema process R is in 2NF if it is in 1NF and each non-prime attribute A in R is fully functionally related on primary key. Second normal form (2N
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define attribute inheritance with example?
CREATE TABLE prodtrans ( pno number (4) ptype char (1) CHECK (ptype in ('I','R','S')), qty number (5) FOREIGN KEY pno REFERENCES product (pno) ON DELETE CASCADE);
Define Cascading rollback The phenomenon where a single transaction failure leads to a series of transaction rollbacks is known as Cascading rollback.
Object-based Models: Use objects as key data representation components . Examples:- Entity-Relationship Model: It is a collection of real world objects known as entitie
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