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The relational algebra expression equivalent to the following tuple calculus expression:

$\left\{t \mid t \in r \land \left(t[A] = 10 \land t[B]=20\right)\right\}$ is

  1. $\sigma_{(A=10 \lor B=20)} (r)$

  2. $\sigma_{(A=10)} (r) \cup \sigma_{(B=20)} (r)$

  3. $\sigma_{(A=10)} (r) \cap \sigma_{(B=20)} (r)$

  4. $\sigma_{(A=10)} (r) - \sigma_{(B=20)} (r)$

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Best answer

Answer: (C)

Tuple $t$ should have two attributes $A$ and $B$ such that $t.A = 10$ and $t.B = 20.$

So, (Tuples having $A = 10) \cap ($ Tuples having $B = 20) = ($Tuples having $A = 10$ and $B = 20).$

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2 Comments

Could we have in option 'a' in place of or operator and operator
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then both a and c will be correct option.

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Answer:

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