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))}
In case of entity integrity, the primary key may be declared? In a case of entity integrity primary key may be not Null.
Derived horizontal fragmentation: Some applications may include a join of two or more relations. If the relations are stored at dissimilar locations, there may be a major overhead
Illustrate the class diagram for class room scheduling system If in any college, the number of classrooms are limited which have to be allocated to various classes and instruct
What is storage manager? A storage manager is a program module that gives the interface between the Low level data kept in a database and the application programs
What are stored and derived attributes? Stored attributes: The attributes keeps in a data base are known as stored attributes. Derived attributes: The attributes that are de
What is a value? A data value is used for identity. This form of identity is used in relational systems.eg: The primary key value of a tuple recognize the tuple.
composite attribute
ddlc
Explain Object oriented Model ? Object Oriented Model - This model is based on the object-oriented programming language paradigm. It involves the features of OOP such as inhe
Define in which normalisation form if an attribute of a composite key is dependent on an attribute of other composite key. Ans: 3NF A relation is in 3 NF if an attribute of
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