Questions tagged [relational-calculus]

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.

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Questions Concerning the Chase Test

For the question above, my work for each of the questions is below the concerns. Here are my main concerns: Does the order in which you use the relations matter? Can you end up with less tuples with ...
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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 ...
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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: {<N&...
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Converting from domain calculus to relational algebra

I have an assigned task at the uni and I have the three relations that follow: Customer (Name, City, Account) Offer (Product_Description, Supplier, Price) Order (Name, Product_Description, Quantity, ...
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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-...
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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 ...
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How to express inclusive and exclusive relations in relational algebra and relational calculus?

Let be the following simplified database sketch: R1(P,S),R2(S,T) and R3(T,S) with P= people S = Sport and T= Sports Center How to find in relational algebra and relational calculus which couples ...
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Find street number of the longest street in each city in Canada

Find street number of the longest street in each city in Canada Relevant relations: City(city-name,country-name,area,population) Street(stno,city-name,length) The keys are bolded My tuple ...