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Explain Record Based Logical Models?
Record-Based logical Models: Also define data at the conceptual and view levels. Unlike object-oriented models, are used to state overall logical structure of the database, and gives a higher-level description of the implementation. Named so since the database is structured in fixed-format records of various types. Each record type defines a fixed number of fields, or attributes. Each field is commonly of a fixed length (this simplifies the implementation). Record-based models do not involved a mechanism for direct representation of code in the database. Separate languages related along with the model are used to express database queries and updates. The three most widely-accepted models are the relational, network, and hierarchical.
What is the aim of logical schema ? The main motive of the logical schema is to ensure the portability of procedures and models on various physical schemas at runtime.
A super key is an attribute or set of attributes used to recognize the records uniquely in a relation. For instance, in the Relation PERSON defines earlier PERSON_ID is a super
10A.53 Code an Oracle Database trigger to enforce the constraint that an employee can never change his or her department. 10A.54 Code an Oracle Database trigger to allow the
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);
Construct a clean ans concise ER diagram for the database indicating the cardinality mapping for Employee management syatem
All edges of a cube are expanding at a rate of 6 centimeters per second. How fast is the surface area changing when each edge is (a) 2 centimeters and (b) 10 centimeters?
Compare the Nested-loop join and block-nested loop join Ans: Nested loop join - It is costly as worst case cost, no. of block accesses needed is n r * b s + b r where b
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Explain the differences between structured data and unstructured data. Structured data are facts concerning objects and events. The most significant structured data are numeric
What is a shadow copy scheme? It is simple, but efficient, scheme known as the shadow copy schemes. It is based on making copies of the database called shadow copies that singl
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