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Define the concept of aggregation. Give two examples where this concept is useful.
Ans: Aggregation transforms a relationship among the objects into a higher-level object. A new data type known as aggregate is developed which, under specific criteria of "well-definedness," defines aggregation abstractions. Relational databases illustrated as collections of aggregates are structured like a hierarchy of n-ary relations. To keep well-definedness, update operations on such type of databases must keep two invariants. Well-defined relations are different from relations in third normal form. It is displayed that these notions are complementary and both are significant in database design. A top-down method for database design is described that separates decisions concerning aggregate structure from decisions concerning key identification. It is suggested that aggregate types, and other sorts which support real-world abstractions with no introducing Key identification.
Use the IRIS dataset that comes with Weka to compare the classification performance of the following algorithms. 1. NaiveBayesSimple 2. MultiLayerPerceptron J48 (
FDs in Relationships: Enrols Relationship: None as it is many to many Teaches Relationship : Course code → Instructor Instructor → Course code The next question is:
4. Describe three ways to handle missing field values
Why do so various organizations use MySQL? Advantages: Open source Highly efficient Offers a high scalability in terms of size and connectivity. Highly prote
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
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Give the reasons for allowing concurrency? The reasons for allowing concurrency is if the transactions run serially, a short transaction might have to wait for a preceding long
Logical Operators Rules of Precedence: Order evaluated Operator 1 All comparison operators 2
Which two tools are used to administer users for Active Directory?
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