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Differentiate between various levels of data abstraction?
Data Abstraction - Abstraction is the procedure to hide the irrelevant things from the users and represent the relevant things to the user. Database systems are frequent used through non-computer professionals so in which the complexity must be hidden from database system users. This is done through defining levels of abstract as that the database may be viewed; there is logical view or external view, conceptual view and internal view or physical view.
1. External View - This is the highest level of abstraction as seen through a user. It describes only the part of whole database, that is relevant to a particular user.
2. Conceptual View - This is the next higher stages of abstraction that is the sum total of Database Management System user's views. It elaborates what data are in fact stored in the database. It contains information about whole database in terms of a small number of associatively easy structure.
3. Internal View - This is the lowest level of abstraction. It elaborates how the data are physically stored
What is the need for triggers? Triggers are useful mechanisms for alerting humans or for starting particular tasks automatically when particular conditions are met.
Identify the need and use of data control through problem solving, illustration
What it creates while a primary key is combined with a foreign key? It creates Parent-Child relation ship between the tables that connect them while a primary key is combined w
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employee(empid,empname,dept,telno,mobno, add,sssno,tinno,WEdates,WEcomp,WEadd,WEpos,WEres) this is a employee record which is need to be normalize.the WE means work experience
Question: (a) Discuss the difference between a composite key and a composite attribute. How would each be indicated in an E-R diagram? Support your answer with appropriate exam
Explain data dictonary on oracle ? Data Dictionary - Data dictionaries are the system tables in which contain descriptions of the database objects and how they are structured.
Question 1 Explain ER model Question 2 What are the characteristics of a computer provided information? Question 3 What are facts and guidelines to be considered when se
what is er digram given that example of hospital,bank and library er digram.
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