For questions: (a) about one of the relational forms of predicate calculus, i.e., domain and tuple, or (b) about expressing queries on data contained in a relational database utilizing one of those forms of calculus.
Questions tagged [relational-calculus]
20 questions
6
votes
1 answer
Find the highest graded student using Tuple Relational Calculus
Suppose I have a table of students, containing their ID and their grade:
-----------------
| id | grade |
-----------------
| 1 | 83 |
| 2 | 94 |
| 3 | 92 |
| 4 | 78 |
How do I write a Tuple Relational Calculus…
CodyBugstein
- 253
- 1
- 3
- 10
6
votes
2 answers
What are the practical uses for relational calculus?
In my Database Design course we are learning both Relational Algebra and Relational Calculus. I can see where Relational Algebra could be useful since it is closely tied to SQL.
Our professor said that Relational Calculus was used as an alternative…
joshuadrs
- 63
- 3
5
votes
2 answers
Creating relationships between tables that where not specified in the given UML diagram
Good evening!
I'm working on designing my very first actual database from the following UML class diagram (in French unfortunately):
I'm at the point of creating the relational sketch of it which I created this way:
Yet, it creates some issues…
Revolucion for Monica
- 677
- 2
- 11
- 27
3
votes
1 answer
Declarative and Procedural Query Languages
In the book Database System Concepts 6th Edition, Chapter 2 (Relational Algebra), it states that there are three formal query languages, the relational algebra, the
tuple relational calculus and the domain relational calculus, which are declarative…
Mohammed Ali Melhem
- 33
- 2
3
votes
1 answer
Questions Concerning the Chase Test
[5 Marks] Let R(A,B,C,D,E) be decomposed into relations with the following three set of attributes {A,B,C}, {B,C,D}, and {A,C,E}. For each of the following sets of FD's, use the chase test to tell whether the decomposition of R is lossless. For…
Niroosh Ka
- 55
- 6
3
votes
0 answers
Counting in Tuple Relational Calculus
Given the following schema:
Staff (sid, sname)
Project (pid, pdesc, pfrom, pto)
Asset (aid, acat, adesc)
Workfor (sid, pid, wfrom, wto)
Assignment (aid, sid, pid, afrom, ato)
Note: The bold attributes are the keys.
Find the names of the staffs who…
Kyoma
- 131
- 2
3
votes
0 answers
Difference Between Implication and Conjunction in Domain Relational Calculus
I was reading my notes, and I came across this:
Another example would be to find the names of the lecturers teaching all modules. We might reach for the following incorrect expression:
{ | ∃M ∀C ∀MN ∀Cr (lecturer(M, N) ∧ module(C, MN, Cr) ∧…
fer
- 91
- 1
- 5
2
votes
1 answer
TRC: Select an ID if it appears on all measurements
I have these two "tables":
Station (station_id, city) // Stations details
Rainfall (station_id, date, amount) // Rainfall measurements
With Tuple Relational Calculus (TRC), I need to get the IDs of all stations that have related…
Itay
- 123
- 4
2
votes
1 answer
Confusion with Tuple Relation Calculus Operations
I came upon a question like,
Given the following relational schemas
Student (studId, name, age, sex, deptNo, advisor)
Department (deptId, DName, hod, phoneNo)
Which of the following will be the tuple relational calculus query to obtain the…
lu5er
- 123
- 4
2
votes
0 answers
Converting from domain calculus to relational algebra
At university I have been given these three relations:
Customer (Name, City, Account)
Offer (Product_Description Supplier, Price)
Order (Name, Product_Description, Quantity, Supplier)
and this domain calculus:
{Name, City | ∃ Account,…
Anes
- 63
- 1
- 3
2
votes
1 answer
Converting SQL to Relational Algebra / Calculus
I have designed a schema and generated a few SQL queries. I'm using PostgreSQL.
For example:
CREATE TABLE train
(
train_code SERIAL PRIMARY KEY,
name TEXT NOT NULL
);
CREATE TABLE journey
(
journey_id SERIAL PRIMARY KEY,
int INTEGER,
…
Dino Abraham
- 127
- 1
- 1
- 3
1
vote
2 answers
What does <> mean in Relational Calculus?
I saw a Tuple Relational Calculus formula, and it contained the symbol <>.
What does it mean?
CodyBugstein
- 253
- 1
- 3
- 10
1
vote
1 answer
How can I calculate the cost of the query, if there is a `between` condition?
How can I calculate the cost of the query, if there is a between condition?
Select *
From A
Where A.id between 10 and 50
If Index not exists and there is only one condition:
Search in B+ tree to find the first block that meets the condition…
Shir K
- 197
- 1
- 7
1
vote
0 answers
Find names of persons who own at least one house in each city in Canada using tuple relational calculus
I am working on the following exercise:
Using tuple relational calculus, find names of persons who own at least one house in each city in Canada.
The relevant relation schemas are:
City (city-name, country-name, area, population)
House…
Mandy
- 11
- 1
1
vote
0 answers
Quantifiers in Tuple Relational Calculus (Existencial and Universal)
Suppose this state for the relation schema Company
I'm stuck trying to understand how, why and when I should use Quantifiers (Existencial and Universal)
Examples:
Here I understand how the existencial is working, all the formula bounded …
