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))}
Describe the benefits of OOD techniques OOD techniques are very useful for development of large and complex systems. It has been noted that large projects that are developed u
Q. Define a weak entity set and its identifying relationship. List the necessary conditions for a meaningful identifying relationship set of a weak entity set. Entity is a t
What are the advantages and disadvantages of merging an association into a class? Advantages: i) Less number of tables ii) Faster performance due to the fewer tables
describe objectivde of file organisation
OPENCART - Want Massive amount of products Imported through CSV We have a massive list of products that would take completely too long to do data entry. We require a slick progr
Define Timestamp ordering Ans In timestamp-based method, a serial order is made among the concurrent transaction by assigning to every transaction a unique nondecreasing number
What is NULL? Simply NULL means not in value.
What is an Operand? The data on which the operation is to be performed is known as an Operand
What is normalization? It is a method of analysing the given relation schemas based on their Functional Dependencies (FDs) and primary key to attain the properties (1).Minim
What are the benefits of decomposing a system? The benefits of decomposing a system into subsystems are that after decomposition, each individual component become smaller and 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