tuple-relational-calculus

Reversing steps, Converting SQL query back to tuple relational calculus?

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问题 Not sure it is a correct SQL and would like to work backward converting SQL back to tuple relational calculus to check the correctness. Let's say we come up this query to display the classes where all its requirement classes have been complete by all the participants who finished the introduction. So we have two tables, progress and requirement. where progress: mId (string), cId (string) and requirement: : cId (string), rId (string) all the enrollment are kept in progress and all the

Difference between Relational Algebra and Relational calculus

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问题 What is the exact difference between relational algebra and relational calculus. At most of the reference, it will be Relational algebra is procedural and calculus is non procedural . So, what is these stands for. However, we can solve all the problems using relational algebra. Then why we would use relational calculus. Except definition, Explanation with example is much appreciated. 回答1: TL;DR: Queries calling RA (relational algebra) operators & queries of the two relational calculi (RCs)

Difference between Relational Algebra and Relational calculus

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How would I find the highest/largest of something with relation algebra, domain relational calculus and tuple relational calculus

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问题 This is part of a homework assignment. I've got several questions asking find the eid of the employee with the highest salary, or 2nd highest salary. Find the pilot that is certified for the most aircrafts. I don't have any idea on how to do it. There aren't any examples in the chapter, and google is proving less that helpful. If someone could show me how to do just one of these, it'll help a lot. here are the tables: Aircraft( aid : integer, aname : string, cruisingrange : integer )

Difference between Relational Algebra and Relational calculus

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What is the exact difference between relational algebra and relational calculus. At most of the reference, it will be Relational algebra is procedural and calculus is non procedural . So, what is these stands for. However, we can solve all the problems using relational algebra. Then why we would use relational calculus. Except definition, Explanation with example is much appreciated. TL;DR: Queries calling RA (relational algebra) operators & queries of the two relational calculi (RCs) TRC (tuple RC) & DRC (domain RC) are different syntax for the same thing: a relation value or the property