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

asked in Databases by Veteran (52k points)
edited by | 1.7k views

1 Answer

+20 votes
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 $B = 20).$

answered by Boss (33.8k points)
edited by
Answer:

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