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.
What is called mirroring? The simplest approach to introducing redundancy is to duplicate each disk. This method is called mirroring or shadowing.
Define Hash files organization a. Hashing includes computing the address of a data item by calculating a function on the search key value. b. A hash function h is a functi
write program
Which file organization provides very fast access to any arbitrary record of a file? Hashed file organization provides very fast access to any arbitrary record of a file.
Q. Explain data aggregatio n and discuss different design constraints. Sol. Aggregation One limitation of the E-R model is that it cannot express relationships amon
What do you mean by atomicity and aggregation? Atomicity : Either all actions are carried out or none are. Users should not have to worry about the effect of incomplete trans
anyone have a textbook solutions case fair, 8 edition of vol 1 ?, please give me
When are two schedules said to be view equivalent? Ans: Two schedules that is denoted as S and S' are said to be view equivalent if the subsequent three conditions are met
What are the different kinds of database end users? Discuss the major activities of each? End-Users - End-users are the people whose jobs need access to the database for que
What are the different integrity constraints in RDBMS? The various integrity constraints in RDBMS are as: Primary Key: primary key is a grouping of one or more attributes
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