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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.
Give an example of multiple inheritance. One example of multiple inheritance is a committee for students affair which include faculty and administrative staff member.
Explain trivial dependency? Functional dependency of the form α ->β. is trivial if α C β. Trivial functional dependencies are satisfied by all the relations.
The scenario You have been approached to design and implement a prototype of a distributed information system for a national car part retail outlet chain. The company comprises
Example- Search the salary of employees who are not 'ANALYST' but get a salary below than or equal to any people employed as 'ANALYST'. SELECT EMPNO, ENAME, JOB, SAL FROMEMP
What is RDBMS terminology for a row? A tuple is a RDBMS terminology for a row
Type of views : Simple views and Difficult Views Feature Simple Views Complex Views Number of tables One
the of super market system done in database
Consider entity type Employee with attributes empNumber (this is unique), empName, and the year when he/she was hired. An employee can either be a technical employee, a marketing e
discuss the purpose of the concurrency control?
Which language used in application programs to request data from the DBMS is referred? Language which is used in application program is DML to request data from the DBMS is ref
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