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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 a disjoint less constraint? Ans: It needs that an entity belongs to no much more than one level entity set. Disjoint less constraint needs that an entity belongs to
Using SQL create a view RS for the relations R and S. The view consists of the columns A and D renamed as X and Y in that order. Insert a tuple into it. Show the contents of t
Which method of access uses key transformation? A Hash method of access uses key transformation.
Association as a cache This association must be updated when any new element is added to it, but testing for overlap using association is more efficient. Figure:
What are the benefits of OOA technology? Using OOA technology can produce many benefits, such as: i) Reusability of code ii) Productivity is gained through direct mappi
Describe Specialsation and generalization? Specialisation /generalization: This is a top down and bottom up approach to the design of database. It displays the IS_A relation
You are required to implement integrity constraints within the database to enforce the following requirements: For Projects: Start date must be supplied. Start date cannot be i
Shared lock or Read Lock It is requested by a transaction that needs to just read the value of data item. A shared lock on a data item does not permit an exclusive lock
Project: Microsoft Access You have been asked by the ABC Tanning Salon to create a database that can be used to track the salon's customers. You are to create a table in Access
Let us first describe the term relationships. What Are Relationships? A relationship can be defined as: A set of associations or connection, or A rule for communic
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