Consider student (name, sex, marks) is relation where name is primary key then…
Consider student (name, sex, marks) is relation where name is primary key then the following relational algebra expression.
π name (σ sex=’female’ (student)−(π name (student)⋈ ρ n,x,m (student) on sex=’female’ ∧ x=’male’∧ marks≤m) produces
Answer: C. Names of girls with marks more than all the boys — This expression is selecting the names of female students σ sex=′female′ and subtracting the names of female students who have marks less than or equal to…
- A.
Names of girls with highest marks
- B.
Names of girls with more marks than some boy
- C.
Names of girls with marks more than all the boys
- D.
Names of girls with marks not less than some boy
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Correct answer: C
This expression is selecting the names of female students σ sex=′female′ and subtracting the names of female students who have marks less than or equal to some male student (marks≤m).
Therefore, the expression produces:
c) Names of girls with marks more than all the boys
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