Questions tagged [relational-calculus]

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Normal form after decomposition of a relation

I came across a text recently which claims that if we perform a lossless decomposition of a relation R into smaller relations R1 and R2, and if R is in 3NF, both R1 and R2 are 3NF. I felt a bit ...
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Whether same output is obtained for the two queries

Consider the following SQL Queries executed on the relation Employee: Employee (Eid, Ename, sal) Eid is the primary key Queries: S1:SELECT count (*) FROM Employee; S2: SELECT count (Eid)...
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Normal form of relation R

It is given that for a relation R all the attributes of the relation appear in some of the candidate keys. It is also given that there is only one compound candidate key which exists for a relation, ...
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Relational calculus to SQL

I am somewhat aware of the correspondence between (tuple and domain) relational calculus, relational algebra, and SQL. To the best of my understanding, one should be able to automatically convert a ...
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Relational calculus expression for projection (Database Management)

I recently came across this question: Let the following relation schemas be given: $R=(A,B,C)$ $S=(D,E,F)$ Let relations r(R) and s(S) be given. Give an expression in the tuple relational calculus ...
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Use of existential quantifier in tuple relational calculus

It is somewhat confusing to me when to use quantifiers in tuple relational calculus (TRC). I stumbled upon following problem and I am still scratching my head thinking why not TRC query can be ...