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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.
Using Literal Character String Example: To print IS A as one string with column name employee SELECT ENAME || ' IS A ' || JOB AS "EMPLOYEE" FROM EMP;
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what is entity in database system?
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What is a recursive relationship? Give an example not used in the text. A recursive relationship is a relationship among an entity and itself. For example, given the entity PER
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Describe sequential file organization. Explain the rules for (i) Inserting a new record. (ii) Deleting an existing record. Ans:A sequential f
Explain the Attribute inheritance Ans: Throughout the rendering of the objects in a view, attribute sets of objects higher in the view hierarchy are inherited via objects below
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