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What is completeness constraint on generalization? Define the variation between total and partial design constraint. Give an example each.
Ans: Completeness Constraints
1. Total specialization constraint
a. Each entity in the superclass should be a member of some subclass in the specialization for example {HOURLY_EMPLOYEE, SALARIED_EMPLOYEE}
b. Notation: superclass
2. Partial specialization constraint an entity might not belong to any type of the subclasses
For example: {SECRETARY, ENGINEER, TECHNICIAN}
Define instance and schema? Instance: Collection of data stored in the data base at a certain moment is Schema: The overall design of the data base is known as the data base
The PROJECT operation The project operation is used to choose the records with specified attributes as discarding the others based on some related criteria. This is denotes as ∏
Normalization :It is a process of examine the given relation schemas based on their primary key and Functional Dependencies (FDs) to achieve the properties Minimizing redun
Hierarchical model is also known by? A hierarchical model is also known as a Tree structure.
Normal 0 false false false EN-US X-NONE X-NONE
examples of fields in a database
What are the ways of obtaining the connection parameters? Hardwire the parameters into the program. Ask for the parameters interactively. Get the parameters
What are the aggregate objects in the data dictionary? Views Match codes Lock objects.
The File Based System File based systems are an early attempt to computerise the manual filing system. For example, a manual file can be set up to hold all the correspondence r
Q. Explain the terms key constraints participation constraints and mapping caradinalities in ER model. Participation Constraints : The participation of an entity set E i
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