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!
Consider the subsequent relation schemes:
Project (Project#, Project_name, chief_architect)
Employee (Emp#, Empname)
Assigned_To (Project#, Emp#)
Give expression in Tuple calculus and Domain calculus for each of the queries below:
(i) Get the employee numbers of employees who work on all projects.
(ii) Get the employee numbers of employees who do not work on the COMP123 project.
Ans: (i) Tuple Calculus:
{t[Emp#] | t ∈ ASSIGNED_TO ∧ ∀p (p ∈ PROJECT ∃u (u ∈ ASSIGNED_TO ∧ p[Project#] = u[Project#] ∧ t[Emp#] = u[Emp#]))}
Domain Calculus:
{e | ∃p (
∈ ASSIGNED_TO ∧ ∀p1 ( ∈ PROJECT ∈ ASSIGNED_TO))}
(ii) Tuple Calculus:
{t[Emp#] | t ∈ ASSIGNED_TO ∧ ¬∃u (u ∈ ASSIGNED_TO ∧ u[Project#] = 'COMP123'∧ t[Emp#] = u[Emp#])}
∈ ASSIGNED_TO ∧ ∀p1, e1 ( ∉ ASSIGNED_TO ∨ p1 ≠ 'COMP123' ∨ e1 ≠ e))}
Define check point and its impact on data base recovery. Ans: There could be hundreds of transactions handled per minute, in a large on-line database system.
Dependency Preservation It is obvious that the decomposition must be lossless so that we do not lose any information from the relation that is decomposed. Dependency preservati
What is serializability? Explain its types? The data base system must control concurrent implementation of transactions, to ensure that the data base state remains consistent.
A relation instance indicates as r is a collection of tuples for a given relational schema at a exact point of time. A relation state r of the relation schema R (A 1 ,A 2 ,.....
I need help with data warehousing and business intelligence course project about designing a data warehouse for a jewelry company that does not have one
assume we have the following apllicationthat model sccer team the games they play and the players inv each teamin the design we want to capture
i need help for assignment ..
What is the meaning of Recovery? In deferred update methods, if a transaction fails before arriving its commit point, it will not have altered the database in any way, so UNDO
what is the relationship between receipt and owner entities in computer sales and service company
What is a PROJECT operation? The project operation is a unary operation that returns its argument relation with particular attributes left out. Projection is shown by pie (π).
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