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What is data model? Explain object based and record based data models?
Ans: A data model is an abstract model in which describes how data is represented and accessed.
(i) Object based data models: Same to a relational database model, but objects, classes and inheritance are directly supported within database schemas and in the query language
(ii) Record based data models: is a database model based on first-order predicate logic. Its core idea is to elaborate a database as a collection of predicates over a finite set of predicate variables, describing constraints on the possible values and combinations of values.
Although how will the system recover The selection of REDO or UNDO for a transaction for the recovery is completed on the basis of the state of the transactions. This state is
properties of derirable decomposition
Explain Network Model in DBMS? Network Model - It was formalised within the late year of 1960s through the Database Task Group of the Conference on Data System Language (DBTG
Do NOT use the timestamp type. Use separate date and time data types only. Figure out how to define an SQL insert statement that uses built-in SQL (or MySQL) functions to define
Limitations of File Based System The file-based system has some limitations. The limitations are listed as follows: Isolation and separation of data: When the data is
A Relation Schema represented by R(A1, A2, ..., An) is made up of the relation name the list of attributes and R Ai that it contains. A relation is described as a set of tuples
Illustrate the Deployment Diagram A deployment diagram shows all nodes on network, their processor execution and interconnections. In a dynamic model, this is used to represen
The advantages of a database management system (DBMS) include :- Data integrity and elimination of duplication.
Partial Key : It is a group of attributes that can uniquely identify small entities and that are related to same base entity. It is sometime named as Discriminator. Altern
The following variant of the primary copy asynchronous-update replication protocol has been proposed for totally replicated systems. (a) A transaction executing at site A updat
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