Chapter 6: Problem 11
Define the following terms with respect to the tuple calculus: tuple variable, range relation, atom, formula, and expression.
Chapter 6: Problem 11
Define the following terms with respect to the tuple calculus: tuple variable, range relation, atom, formula, and expression.
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Get started for freeDiscuss the meanings of the existential quantifier \((\exists)\) and the universal quantifier \((\forall)\)
Define the following terms with respect to the domain calculus: domain variable, range relation, atom, formula, and expression.
Discuss the various types of inner join operations. Why is theta join required?
In what sense does relational calculus differ from relational algebra, and in what sense are they similar?
Consider this query: Retrieve the ssns of employees who work on at least those projects on which the employee with \(\operatorname{ss} N=123456789\) works. This may be stated \(\operatorname{as}(\text { FORALL } x)(\text { IF } P \text { THEN } Q),\) where \(\bullet\) \(x\) is a tuple variable that ranges over the PROJECT relation. \(\bullet\) \(P \equiv\) employee with \(\operatorname{ssN}=123456789\) works on project \(x\) \(\bullet\) \(Q \equiv\) employee e works on project \(x\) Express the query in tuple relational calculus, using the rules \(\bullet\) \((\forall x)(P(x)) \equiv \operatorname{NOT}(\exists x)(\operatorname{NOT}(P(x)))\) \(\bullet\) (IF \(P \text { THEN } Q) \equiv(\mathrm{NOT}(P) \text { OR } Q)\)
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