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Let r and s be two relations over the relational schemas R and S respectively, and let A be an attribute in R. Then the relational algebra expression A a (r s) s = >< is always equal to
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- σA = a (r)
- r
- σA = a (r) ⋈ s
- None of these
- σA = a (r)
Correct Option: C
Relational schemas R and S A be an attribute in R.
SA=a (r) ⋈ s
The next step is to select A = in relation
Now, since A is attribute of R and r is also a relation of R.
Here write expression is to be performed.
σA=a (r ⋈ s) = σA=a (r ) ⋈ s
