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 difference between using functions along with and without grouping attributes in relational algebra. Give examples.
Ans: Group functions are used to group data of similar type. GAMMA = grouping and aggregation Applying GAMMAL(R)• Group R according to all the grouping attributes on list L.1. That is: form one group for each distinct list of values for those attributes in R.• Within each group, compute AGG(A ) for each aggregation on list L.• Result has one tuple for each group:1. The grouping attributes and2. Their group's aggregations. Example: Grouping /Aggregation R = ( A B C ) 1 2 3 4 5 6 1 2 5 GAMMAA,B,AVG(C) (R) = ? First, group R by A and B : A B C 1 2 3 1 2 5 4 5 6 Then, average C within groups: A B AVG(C) 1 2 4 4 5 6
What is the difference between internal tables and extract datasets? The lines of an internal table always have the similar structure. By using extract datasets, you can ha
Ask q“A database will be made to store information about patients in a hospital. On arrival, each patient’s personal details (name, address, and telephone number) are recorded wher
Multiple column Queries: Syntax: SELECT COLUMN1, COL2,...... FROM TABLE WHERE (COLUMN1, COL2, ...) IN (SELECT COLUMN1, COL2,.... FROM TABLE WHERE );
Niles Video Inc. wants to create a website for online sales of movies (DVD and videotapes). People will be allowed to register as customers on the website and to update their store
What is known as a search key? An attribute or set of attributes used to look up records in a file is known as a search key.
Explain weak and strong entity type ? Weak and Strong entity type: An entity set which does not have a primary key is referred to as a weak entity set. The existence of a wea
How does the system cope up with a record crash when recovery is going on after the first crash? Ans: In a system the undo and redo operations are needed to be idempotent to c
Given the following relations Vehicle (Reg_no, make, colour) Person(eno, name, address) Owner(eno, reg_no) Write expressions in the relational algebra to answer the following
Different stages of DDLC ?
Event Occurrence of a process is called event. In other words, the object can receive many input instructions. The changes which occur due to these instructions are known as e
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