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!
Explain the concept of QBE?
Query-by-example represents a visual/graphical approach for accessing information in a database by the use of query templates called as skeleton tables. It is used through entering example values directly within a query template to represent what is to be achieved. QBE was developed at IBMs. T.J. Watson Research Centre and it is used through many database systems for personal computers. QBE is an extremely powerful facility that gives the user the capability to access the information a user needs without the knowledge of any programming language.
Queries in QBE are expressed through skeleton tables. QBE has two distinct features:
- QBE has two-dimensional syntax: Queries look like tables.- QBE queries are expressed "by example". Instead of giving a process for obtaining the desired answer, the user provides an example of what is desired.An example of QBE is given asEMPNO NAME SALARY DESIG DEPTNO P..x "Manager"
This query tells the system to such as for tuples in EMP relation which have designation Manager. For each such tuple, the system assigns the value of the Ename attribute to the variable x and prints it.
Determine the Persistent object Persistent object can be stored in one of the following: Files Cheap, permanent, simple storage Low level (Write, Read) Ap
During the deletion of a tuple two cases can happen: Deletion of tuple in relation having the foreign key: In this type of case simply delete the desired tuple. For example, in
Domain Constraint It shows that each attribute in a relation has to contain an atomic value only from the corresponding domains. The data types associated with commercial RDBMS
A step-wise distributed database design methodology Following is a step-wise methodology for distributed database design. (1) Examine the nature of distribution. Find out wh
After the completion of the logical model the physical model is to be made. The oracle 10 G will be used as a database server and all the tables with their column are created and i
Your friend owns and operates a wholesale shoe business with annual revenues of $5 million dollars. His wholesale business specializes in supplying and supporting retailers with sh
What is trigger Triggers are statements that are implemented automatically by the system as the side effect of a change to the database.
How does a query tree represent a relational algebra expression? Ans: This includes transforming an initial expression (tree) into an equivalent expression (tree) that is
Process of implementing system design in dynamic models There are three essential approaches to implementing system design in dynamic models. These approaches are as below:
As with other software, databases can potentially be used for unethical purposes. As a database developer, and a consumer, you should recognize database misuse, and how it may affe
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