Already have an account? Get multiple benefits of using own account!
Login in your account..!
Remember me
Don't have an account? Create your account in less than a minutes,
Forgot password? how can I recover my password now!
Enter right registered email to receive password!
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
Differance between internal and external schema? Internal and external schema: Internal Schema • Describes the physical storage structure • Uses a physical data model External
Mixed fragmentation: Sometimes, horizontal fragmentation or vertical fragmentation of a database schema by itself is insufficient to sufficiently distribute the data for some appli
What is a foreign key, and what is it used for? A foreign key is used to establish relationships between relations in the relational model. Technically, a foreign key is a colu
(a) Why did SAP introduce the extended star schema?
Accessing information about permissions to all users- Object level permissions: With the use of data dictionary you can see the permissions to user. Let us get the table name fro
In this practical assignment, we will run through a complete database application development cycle, starting with the schema design, from an initial data import to database applic
Aggregate functions Some of these functions are min, count, max, and avg. These functions help in getting consolidated information from a set of tuples. Example:
4. Describe three ways to handle missing field values
DDL Compiler The DDL compiler changes the data definition statements (such as CREATE TABLE .... in SQL) into a set of tables having metadata tables. These tables have infor
Describe the definition of a transaction in SQL Ans: The SQL transaction starts implicitly. Transactions are finished by either Commit work that commits the transaction and st
Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!
whatsapp: +91-977-207-8620
Phone: +91-977-207-8620
Email: [email protected]
All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd