The Gateway to Computer Science Excellence
First time here? Checkout the FAQ!
+14 votes

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 (59.5k points)
edited by | 1.2k views

1 Answer

+15 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 (34k points)
selected by

Related questions

Quick search syntax
tags tag:apple
author user:martin
title title:apple
content content:apple
exclude -tag:apple
force match +apple
views views:100
score score:10
answers answers:2
is accepted isaccepted:true
is closed isclosed:true

38,039 questions
45,533 answers
48,848 users