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Explain what is Aggregation?
Aggregation: Aggregation is an significant concept in database design whereas composite objects could be modelled during the design of database applications. Thus, preserving the aggregation concept within database implementation is must. we propose models for implementation of aggregation in an Object-Relational Database Management System (ORDBMS) through the use of index clusters and nested tables. Aggregation refers to an abstraction in that a relationship among objects is regarded as a higher-level object.
Complete replication: It implies maintaining of a whole copy of the database at every site. Thus, the reliability & availability and performance for query response are maximized.
Draw an ER diagram that represents the information described below. Show all entity sets, relationship sets, primary keys, and the mapping cardinality of the relationship sets.
diagrams and meaning
What is a view in SQL? When can views be updated? A view is a virtual table which consists of columns from one or more tables. Through it is same to a table; it is stored in
Concurrency issues Data integrity: Threads accessing same object need to be synchronized, such as: banking account. Deadlock: One or more threads in system are perman
Problem: ‘Users and Information system specialists need to spend inordinate amounts of time locating and gathering data' (Watson and Hal, 1998) Recent developments in the ar
Give the forms of triggers? The triggering event can be insert or delete. For updated the trigger can state columns. The referencing old row as clause The referencing
What is object identity? An object retains its identity even if some or all the values of variables or explanations of methods change overtime.
What is Interaction Diagram An interaction diagram shows an interaction, comprises of a set of objects and their relationships including the messages that may be dispatched be
Define multivalued dependency. What do understand by trivial multivalued dependency? Ans: A multivalued dependency is a full constraint among two sets of attributes in a rela
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