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!
Draw and explain the three level architecture of the database system?
A DBMS gives three levels of data is said to follow three-level architecture. The trget of the three-schema architecture is to divide the user applications and the physical database. The view at each of these stages is described through a schema. The processes of transforming requests and results among levels are known as mappings. In this architecture, schemas can be described at the subsequent three stages:
External Level or Subschema - It is the highest level of database abstraction whereas only those portions of the database of concern to a user or application program are involved. Any number of user views (some of which may be identical) might exist for a given global or conceptual view. Each external view is described through means of a schema known as an external schema or subschema.
Conceptual Level or Conceptual Schema - At these stages of database abstraction all the database entities and the relationships between them are included. One conceptual view represents the whole database. This conceptual view is described through the conceptual schema. There is only one conceptual schema per database. The description of data at that level is in a format independent of its physical representation. It also involves features which specify the checks to retain data consistency and integrity.
Internal Level or Physical Schema - It is closest to the physical storage technique used. It denotes how the data will be stored and elaborates the data structures and access techniques to be used through the database. The internal view is expressed through the internal schema.
Why older data models are being replaced by new data modelling 100 words accepted#
Which operations need the participating relations to be union compatible? A UNION, INTERSECTION and DIFFERENCE operations need the participating relations to be union compatibl
What is banker's algorithm? Banker's algorithm is a deadlock avoidance algorithm that is applicable to a resource-allocation system with multiple instances of each resource ty
This language that enable user manipulate to or access data as organized by appropriate data model. Low level or Procedural DML : DML needs a user to specify what data ar
Define decision tree classifiers? As the name suggests decision tree classifiers use a tree: Every leaf node has an associated class, and every internal node has a predicate as
Why 'AS' clause is used in SQL ? 'As' clause is used for Rename operation. ‘AS' clause is used in SQL for rename operation. (e.g., SELECT ENO AS EMPLOYEE_NO FROM EMP)
Discuss the methods for a hash file to expand and shrink dynamically. What are the advantages and disadvantages of each? The hashing methods that permit dyanamic file expansi
Column Constraints: NOT NULL, UNIQUE, CHECK, PRIMARY KEY, DEFAULT, REFERENCES, On delete Cascade : Using this key whenever a parent row is removed in a referenced
Give the levels of data abstraction? There are three levels of Data Abstraction a) Physical level b) logical level c) view level
Consider the subsequent relation Professor (Pfcode, dept, head, time) It is assumed that (i) A professor can work in much more than one
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